You may want to keep your feelers out for any other issues he might have around social interaction (eg, eye contact, waving bye-bye, playing pat-a-cake). In a couple months if nothing changes, it can't hurt to have him evaluated by a specialist.
My daughter had exactly the same issues and almost everyone told me to wait for her to "grow out of it", or that they had a nephew who didn't speak until he was three, why is everyone so quick to pathologize infants, etc. When she was two and a half, she started receiving speech and OT through IL's Early Intervention programming. By her third birthday she doubled her expressive/receptive language levels.
I know the whole concept is incredibly daunting, and I'm in no way implying your child is "delayed" or anything like that. It's more like, why the hey not, the eval is free. If it's all good, then you can put your mind at ease. If there's something up, trust me, you want to deal with it sooner rather than later.
Good luck and let me know if I can be of further help.