Some one decided to try him out the other day (I was NOT present for this, but my partner was) and apparently Shortie bucked this guy off. The story I heard was he asked Shortie to canter, Shortie tossed his head and refused to break gait so the guy smacked him with the end of his reins behind the girth and apparently Shortie started bucking and didn't stop until this guy was off him. I got on Shortie the next day (I was out of town) and he was perfect with me - did all his transitions no problems, head low, not even the HINT of an issue. Now, he has NEVER EVER offered to buck with me. He's never even seemed to think about it! He has his days where he's a little lazy and even I've popped him with the end of the reins and all he did was toss his head a bit at that but he transitioned.
Then what I thought was a fluke incident happened again. Some one else came to try him, and he tried to buck with them too. They were a more experienced rider and was able to immediatly correct him though.
Both these people used the tack I use every single day with him, so there were no issues where maybe it was tack fit. I even rode him before hand with the second person to demonstrate how well behaved he is! So much for that!
Could I be the reason he's like this now? I hate to think I made him into a one person horse. I never meant for it to happen. :( Any advice????