Muscle memory here too, to the point that I'll unconsciously do it even when I'm just sparring with one other person in a private battle or in recon.
I'm also That over-eager coworker in salmon run who just booyahs for literally any reason. If you revive me, if you kill a flyfish, if you kill anything chasing me (especially a steel eel), if you put the last egg in the basket we need to make quota, if you use a special that makes any impact at all, at the start of the wave, at the end of the wave, anything. I used to get self-conscious if no one responded but now I think it just makes me want to do it more until someone responds. I'd rather be viewed as obnoxiously over-eager than too 'cool' to acknowledge others any day.