okay, this is what happend, when i took my head off to change the head gasket, some coolant dripped into my sleeves. i didnt notice, so i waited a day to put the head back on. so today, i looked at my sleeves, and it looked and felt like there was some rust (maybe) on them. the sleeves just felt kinda grainy, but i just kinda rubbed most of it off with my fingernail...should i be worried about this or what? i figure that the heat of the motor will just burn this stuff off, right?