When my son started K4, his teacher asked me the first week if he had OCD issues, because the first thing he did upon entering class every day, was go wash his hands. LOL
He is 12, and I can promise you he is NOT OCD. I think it must just be a phase that some kids go through. He was very "sensory" aware when he was younger, too. He still is fairly sensitive to some things (smells in particular), but the other things he either outgrew, or learned to manage/deal with it (he is vocal about which sheets on his bed are the most comfortable, and the same with his clothing). At no point, however, did any of his heightened sensory awareness cause us to have to alter our lives. He sleeps on all the sheets we have for his bed, for instance, he just has favorites, lol.
In my layperson's opinion, I would say that unless your son is so overwhelmed by these "quirks" to the point that you must intervene and change your routine to make accommodations, then you have nothing to worry about. ;)