I didn't know you could over tighten it. Before I replaced mine I always turned it until it ratcheted and kept going until the handle was paralel to the bike. Never had any trouble opening it and the same on Wendys bike. Pedalmasher had a very good thought on the gas cap opening being changed in 06-07 and maybe the cap wasn't or the cap is adifferent fit than the old ones,who knows.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!