Yesterday I noticed a very loud and constant rattle coming from the left edge of the dash. I found the source location almost instantly and found that if I just applied pressure the rattle would stop, but as soon as I removed my hand it would return. This is from the far left side of the top of the dash just behind the vent area where the piece is rubbery. On subsequent drives the rattle has now disappeared. It seems to have only been on one trip. Any ideas what could cause this?