Is there anything you might have forgotten or that could have seemed weird to him?
In any case, you should bring it up, but not via text message. That's way too easy to misunderstand and it also comes across as accusatory really quick. Better to meet him in person or give him a call - that way you can actually see how he reacts and ask follow-up questions instead of just guessing. The other answers are right that waiting just makes things worse, but there's one thing I think is important: Be prepared for the possibility that there might be something on your end that you didn't realize. Sometimes stupid misunderstandings happen where you don't know what's bothering the other person. That doesn't mean you did something wrong, but being open to hearing it makes all the difference when you bring it up.
Keep it casual, not dramatic. Confronting him directly just comes across as defensive. Just say that you've noticed things feel weird between you two and that you want to know if everything's okay. If he has a hard time talking about it, he can still clam up - but the chance that he'll open up if you don't come across as attacking is just bigger.