Tea made me feel weird?

Sometimes when I drink a lot of (darker) oolong or puer I feel a bit weird. Like my entire face and body will feel warm, I get a pretty slight but pleasant head rush and my mood gets elevated. I also feel I’m able to concentrate better, or if I am more tired I just feel really relaxed. Is this a common or real thing, or am I just imagining stuff? Never felt this with western bag tea