Well... I was unsuccessful with fixing the problem, but I wanted to respond anyway so I wouldn't keep you hanging: I love the art you made here. The style really looks great. <img src="smileys/smiley1.gif" border="0" align="middle" />
As for, y'know, the problem... If no one else comes around to help you, the only thing I can suggest is a work-around. Basically, when the character is facing left, set the arm about 200 pixels higher or whatever it takes to line it up properly. It does work, technically, but you won't understand what the actual problem was in the first place. It's less than ideal, but it's a good back-up.