Green’s Dictionary of Slang

(US campus) an expression of approval of another’s good fortune.

1987		Eble Campus Sl. Spring 4: gotta like that – expression of approval.
1996		Eble Sl. and Sociability 101: College slang has many expressions that help to keep communication and conversation going. [...] Some express agreement, for example, given, gotta love that, I’m down with that.