Making sex better by flexing

I just started getting serious with this guy from work. He's so cool I love being around him. And I wonder if guys can feel it when there inside you and you flex to tighten around them? Because he's never said anything before, but when I get super excited I feel my self flex and he moans, and it's the hottest thing ever. But idk if it's cuz he feels me squeeze or just cuz I'm moaning