Boy I am so glad I'm not dating now a days! Facebook, Twitter, My space (back in the day), snap whatever, blah blah blah! It is all cr@p which cause trouble in relationships and divide people! When you grow up computer sites won't mean anything to you any more. It just adds to the already complicated feelings relationships go through.
It sounds like it to me. He obviously wants to hide something.
I don't know what Snapchat is! Why don't you ask him why?