I wouldn't unless I know the person or he didn't lose much to me but a lot for him like a new guy that lost 200k or something, it's not like he ddosed you or anything.
But I wouldn't tease the guy saying thanks or anything.
Anyways why were you training with a partyhat? Why not use a coif and get more exp/hr?
http://www.youtube.com/watch?v=FBvB9IgAGc8