L., I am so excited that you were able to get your dogs back!! I lost one (got loose from a crate @ a show) for 19 days, & another (got out of a fenced yard @ my father's) for a week.
Neither of mine were caught by people until I found them, & so I know that they weren't held by anyone & mistreated, but they both reverted a bit to feral tendencies (wild dog, untrusting).
Each dog will respond differently, & some breeds have tendencies greater than others.
You didn't mention in your post how long ago they were found & brought home, & whether or not the behavior was immediate, or developed over days/weeks. So I'm going to assume they've been home for a bit of time, & this is something that has become more pronounced.
Obviously, there was a long time that your dogs weren't in the safety of your home, & they are both happy to be home, but also unsure of their new place in the home. Is it secure? Are you (your family) as happy to have them as they are to be home? What happened to them while they were lost?
From your post, it isn't possible to give actual advice on how to handle the problem. Ideally, you need to work with someone that can actually see the interactions that are causing the growling/snapping. Dogs respond to pressure, & pressure can come in many different forms, that we aren't aware of. Hugging a dog, blocking their exit from an area, another dog approaching when they are near what they want (bone, food, human).
So for example, I don't know if your dog is growling because your husband is petting him & hovering too closely, or because your husband is petting him & the other dog is approaching, so the first dog is "guarding" what he views as "his".
Because of this, because of the intricacies of the dogs behavior & the variables at play that MUST be observed by someone trained to spot this & "read" dog's body language & interpretations of their surroundings, I can only recommend that you engage with a trainer for help.
If you are able, set up a video camera to record interactions with the dog ahead of time, as not every situation can be recreated.
In the meantime, be understanding of your dog's situation, recognize specific things that "trigger" him to react, & keep a journal. Think of whether your behaviors around your dogs have changed... maybe you ARE pressuring them by being overtly affectionate (understandable since you are happy to have them home, but it might be too much for him to handle).
Regarding whether you should go to the vet - Physical pain is often exhibited by the dog in their body language first (wimper/whine, favoring a leg, holding themselves off-kilter @ stand, etc). If your dog is not exhibiting physical signs of pain, & the aggressive mannerisms are occuring -without- your physical communication with the dog (touching/holding/moving) chances are the aggression is behavior, & not physical.
I cannot say definitively you do not need to go to the vet, but I would start with a trainer first. They may even see something physical & refer you to a vet. But if it were MY dog, I'd start with a trainer first, because if the vet starts looking into things & you eventually find that there is nothing physical, there has been time gone by that could've been worked through with a trainer. But I am NOT saying you do not need to follow up with a vet. Just don't do so at the exclusion of working with a trainer.
One thing I want to clarify from a post below. Someone mentioned that "this dog needs therapy". This is actually only partially true - understand that by working with a trainer, they will be evaluating the dog & you & the interactions & reactions. Go with the mindset that you/your husband are behaving & interacting in a way that makes the dog uncomfortable, & need to change YOUR behaviors.
As a result of your change, your dog will then respond more positively, until his comfort level reaches an equilibrium. I just don't want you to go into a training environment expecting that the trainer will work with your dog & hand him back & all will be well. It will absolutely need to be a cooperative engagement with you & your dog.
Best of luck, & feel free to PM me with any additional questions.
T. (I have been breeding/training Rhodesian Ridgebacks for 13 years, as well as a student engaged in training/structure/movement of dogs)