Last night the wife came home and pulled the car into the garage (2008 XLR-10/12K). When running at aprox 190 F it was not hot. Turned off motor and coolant started coming out of the 'plastic bottle' at the cap. I understand the 'pressure of the waterpump and the expansion when at rest', but the cap was loose. No service people nor myself have touched that cap, and now it's loose ? My fuel filler cap also 'becomes loose' after driving a few miles. Are these things normal ? I'm sure the motor is not overheating, but why would the 'coolant fill cap, or the fuel filler cap' just BECOME LOOSE ? Thanks.