1999 Accord Coupe - cabin noise

Just wondering if anyone else had this same problem and knows of a fix.
There is kind of a popping/rubbing noise, almost like leather-on-leather. I
finally figured out it was coming from the point where the cloth material
on the roof meets the plastic piece that runs up between the drivers window
and the rear window (2-dr). It is the point right near the top rear corner
of the driver's window (but not a part of the window/door, it is the edge
of the roof lining inside the car).

Anyway, where the plastic and cloth material meet at this point, the cloth
is slightly indented and appears to continue underneath the plastic
piece...it is the same on the passenger side, but it's not making noise
over there. So I can tell the noise is coming from that point, because if I
push my finger on the cloth where it is indented, it makes that same noise.
I'm considering shoving a piece of cardboard up between the two materials
at that point...what else should I try?

Thanks!

DJN