Okay, if you were there by the Game Master's invitation, then the other player was being an incredible jerkass. It's the GM's world - his word is Law. And, IMO, the GM should have been enforcing your welcome - if nothing else, by having some minor disaster befall the player's character until such time as the player straightened up (one of my old GMs had the Cosmic Beams - if you annoyed him, you could hear the Cosmic Beams creaking overhead, and if you kept it up, the Cosmic Ceiling would collapse on your head for massive damage. Randy Milholland, creator of Something*Positive, came up with "Rocks fall, everybody dies," which lives on in the card game Munchkin).
Personally, I blame online "RPGs" - you can badmouth the other players to your heart's content, and 90% of the time they never even know it. Some players seem to have trouble with the idea that in a PnP RPG, not only do you really have to play a character you have defined (as opposed to pushing around the pile of points the computer allows), but your interactions are with real human beings, not computer-controlled NPCs that never take offense at anything.
Sadly, though, it's not that new a phenomenon. Back in the day, before cRPGs, it was less common, but you still had rude players who would start conflict with other players, sometimes over things done in-character (I still remember the night one player got so mad he punched the host's refrigerator and stormed out - because my character had prevented his from doing something stupid that would have gotten us all killed).
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Sodium is a metal that reacts explosively when exposed to water. Chlorine is a gas that'll kill you dead in moments. Together they make my fries taste good.