Have the same problem with my 07, went to dealer and response was to use door more frequently. After explaining the door was used every day he shrugged his shoulders and we still have the problem.
Funnily enough it was to do with the car and not what you may be thinking.
I recently bought a Garmin Nuvi 2460 GPS and one of the accessories is a unit known as a Garmin ecoRoute HD. it connects into the OBDII connector of the car and Bluetooths real time data to the GPS unit. Also...