Definitively set-up. Omar is ready to bust a cap in Tony's ass when his friend (Edwardo I think?) mumbles something to him, and consequently offers Tony an offer that is a great deal more "significant" than the original. A bit too big for Tony's britches, considering all he did was whack Rebenga. Omar knew at the very least Hector was fucked up, and he wanted to get even with the "dishwasher." That's the way I always thought of it.