This is on the roof, towards the rear window on the driver's side. Seems like a clip or something is missing. I may just have my mechanic fix if there's no easy fix.

 

I had the same problem on my '02 LS430, also on the rear of the drivers side. I would push it down and a few days later it would pop back up again.

Stopped by a trusted body shop thinking I needed a clip of some sort. They said they see it all the time in a variety of cars. They took a tube of adhesive (type used for windshields) and put some small drops on the clips that stick up from the roof. They pressed the molding into place, securing it with some masking tape. I removed the tape the next morning and have not had a problem with since.

 

Great! Thanks for the info!

 

make sure t take it down after u put the silicon, or itll pop out and dry that way overnight