I believe everybody has their own boundaries in regards to cheating. I believe that if it makes you feel uncomfortable, that is not a good sign - may it be an overbearing nature of jealousy or actually provoking behaviour from his side. Try to sort it out with him at least, and communicate properly. Trust is the number one rule in a relationship.
I literally talked to a guy about it. Asked to see the conversation and the response I got was him saying I had to trust him and two minutes later he smashed his phone in a million pieces...