The Trek bed should have "locks" available that are used when driving and when sleeping. This will prevent the bed from ever falling down. The bed motors and mounts usually ONLY have a problem if someone tries to lift more than the bed itself, like a child in the bed, or if they do not release the motor activate switch after the bed has gotten to the top or bottom of it's travel.
Checking the service records will tell you about anything that may need maintenance. 50,000 miles is not much to worry about if the necessary service was all kept up to date.
