Man - I do these kind of little breaks all the time. Once I was being too paranoid about cranking down the nuts on my rear wheel and cracked the little retainer washer thing that came with the wheel (not hard to replace, but annoying). I've also destroyed a few old cranks' extractor threads by cranking too hard when the crank-puller wasn't properly threaded in. And I've destroyed two cheap open-face quill stems by wanting to tighten them too much and stripping them. It's annoying as hell, but I don't know how to stop being an idiot.