Strange feeling

Okay so 2 weeks ago my bf went to the movies. I thought nothing of it since he was with his friend(besides me this is the only person near us that he talks to) well strangely he never said who he went with and i have looked through his meassages (we both do when we are bored) and found NOTHING. It just doesnt add up and i havent found a discreet way to ask yet? What should i do??