A.R.
I would not take this lightly. I would take him to see the pediatrician immediately and have him checked for a UTI, and (this is going to sound strange) a throat swab- both rapid and 72 hr strep culture, and if that doesn't come back positive, I would go to a neurologist.
My daughter had wetting issues similar to this and it turns out that she DID have an infection- strep throat. She did not have a sore throat or any symptoms that you would normally see in a child with strep, but her body was fighting itself instead of the strep, which was causing her brain-stem to swell and she was having weird things happen like wetting, some OCD, behavioral changes, sensory issues, sensitivity to light, tics (eye-blinking, sniffing), etc.
The disorder my daughter has is called PANDAS or PITAND, but there are many infections that can affect the brain and cause symptoms like this. Small seizures called petit-mal seizures can also be ruled out with a neurologist.
Again, it's probably nothing major, but I would want to investigate before it goes any further. If he seems unaware that he is doing it/has done it, that is a HUGE red flag to me.
M.