When I had my 2000 trans done at BTS, Brian trashed my factory pan and replaced it with a factory pan which was identical except for two small dimples in the pan. Brian said that a trans flush proceedure can push the filter almost out. He commented that sometimes it is only partially out where the vehicle can be driven, but if it sits overnight, it may not move the next morning. The dimples were added to help hold the filter in position. Not sure when the change was made at the factory. The other possibility is when the filter was last replaced, the old o-ring did not come out with the filter and remained in the valve body. The old o-ring could have prevented the new filter from seating all the way. Dale