"He is." Dean didn't always react the best to certain alpha male types. Oh, he could appreciate the ferocity that was the mutant Wolverine - the older Winchester hadn't made that connection yet - but threaten the younger Winchester the older one got angry. It was a big brother sort of instinct.
"He's also asking because you probably have no idea where you are." Dean lifted his beer in a slight salute before taking a good pull from it. Okay, maybe Dean was in a fighting mood.
"Wait til you find out." Sam would no doubt tell the newbie badass, but that didn't mean Dean automatically had to be civil about it.