This is kinda weird...

When my SO and I have sex, I usually Don't moan...it feels wonderful but I just don't feel the need, you know? Well the other night he asked why I didn't if he wasn't good or was he doing something wrong, then last night when we were having sex, I moaned when it started to feel good and he seemed to enjoy himself more. My question is does anyone else not moan even though it feels good?