I noticed today when I unlocked the driver's side door with the key it opened up ok. I needed to put something in the back seat & it was still locked. First time for this usually all the door unlock the minute the driver's door is unlocked with the key. I tried it later, and it opened them once real slow & wouldn't do it again. Do you have any suggestions where I might look first. I didn't know if there is a tank that might be leaking??