wtf...is this legal?

[Colombo]

I'm playing in a $100 HU on stars today, and the other player, named Glassworks, asks for $10.50 if he loses. Jokingly, i say "yes" just to [censored] with him. Anyway, I win. Two hours later i check my history and it turns out $10.50 from my account was sent to him. I never authorized this, and I think stars support did it. They never asked for my authorization and just sent him money.

wtf?