The metaphor of course is that of a ball that never stays still in the same place.
Socialites priding themselves in being in such high demand that they can't stay too long at your place will use this expression to convey the idea.
By extension, it is therefore a diplomatic way of cutting one's visit short - the implicit idea being "I'd love to stay but I can't, as I've got more obligations for tonight. Sorry!". This is I believe, the meaning in the context you outline.
When employed in a group instead, "Bounce" means "I'm getting bored, let's move on to some other place!" So yes it's slightly negative.
Another way to picture it is to parallel people calling themselves party monkeys with a real party of monkeys bouncing from branch to branch swiftly snatching whatever fruit hangs around on the run.