It would bug me too, even though I try to "be good" and not crazy about other people being on the dot punctual. I'd hate hearing the laughing, because it makes me so self-conscious of how "unfun" my sessions are, and I hate when people are late in general... especially with T, since it's expensive.
Do you think you can talk with him more next week? I'm starting to see that the trick with therapy is that if it bugs you, you probably should bring it up.
I'd think this would be totally fair game, and might be useful/helpful to you. Maybe?
I also think if you don't bring it up... you run the risk of it building up to something bigger in your head, you know? For example, I know that I'm prone to remembering *everything*, not saying *anything*, then suddenly when I get upset enough - having a list of 100 things that someone has been doing wrong to unleash on them
... then it ends up being a bigger, harder to solve problem. Whereas, if you deal with this one thing now... it can be dealt with and over, hopefully.
Good luck...