He introduced me to his friends but acted uncomfortable

He could be nervous about your perception of his friends or their perception of you. Some people get socially stiff when they're worried about judgment. This is fixable and actually pretty common, especially if he otherwise seems into you.

Alternatively, he might be uncomfortable with the label this introduction carries. Bringing someone around friends says something about status and future intent. If he's having doubts or just isn't ready to signal that to his crew, he'll act withdrawn.

Or he doesn't see this going anywhere and the introduction was accidental or obligatory, not a statement. Watch whether he initiates future hangouts with you, especially ones that matter to him. That tells you everything.

Your move is not to address the weirdness unless he does. If you text him about it, you're doing the work he should be doing. You're also giving him an exit ramp by making yourself the problem to solve.

If he texts you asking if you're mad or if it was weird, or if he explains his behavior, then you can reply. Keep it simple and direct. Don't minimize what happened or make excuses for him. Acknowledge it happened, give him one chance to explain himself, and then watch what he does next. A person who actually likes you will either explain and adjust, or own that he was being awkward. Someone unsure will dodge or over-explain in a way that doesn't land.

One awkward introduction might be nothing. A pattern is something else. Give him at least one more interaction with his friends, or one more normal hangout between you two, before you conclude he's ashamed of you or unserious.

If he avoids introducing you to anyone else, stops inviting you to group things, or acts the same way twice, that's when you have enough data. At that point, you can ask directly what's going on. If he can't give you a straight answer, you have your answer. Don't wait more than two or three weeks total for this to become clear. After that, the mixed signal is the signal.