well I would call it overheating if I put candle wax on it and if it melts, I wipe it off quickly and make a mental note [overheating]
Well nothing you're losing there for getting another ESC.
Stock Esky ESC will go sometime. Look into beginners forum and there are like 4 or 6 cases when stock ESC burned frame, motor and battery.

You can also ask Jaketrouble what happend when he changed his HBK2 ESC with Belt-CP's.

Other and easiest option is to watch this clip then the part 2:

http://youtube.com/watch?v=c35lyJnAd5I