Roof leak on non sunroof car?

Went to view a car at a dealer this morning that appeared to have experienced an upward cola explosion from behind the passenger seat.  What was clearly a pair of water marks on the headliner made me get out and check to see if it actually had a pano roof, despite having a fullheadling.  

It didn't,  but the cover strip for the roof-to-body seam had rucked up directly above the two water marks inside. I couldn't lift it further,  but it wouldn't push back down again either. 

It seams (!) that the seam might have split/bubbled to let water in. 

Has anyone else seen or experienced this?

Edited 1 August, 20205 yr by tintinandcharlie