The black plastic strip around my windshield comes loose once in a while after about an hour ant highway speed.  I can pop it back in, but it doesn't feel like it is seated very well, and eventually comes back out.  I am curious to know the function of this piece of plastic.  Is it just cosmetic?  Does it protect from rust and first build up? Am I in danger of the glass coming loose?  Also, how do I fix this.  I am reluctant to use adhesive/sealant, as it seems like it make windshield replacement difficult in the future.  Thanks

 

The windshield is glued in, so that's just a trim piece.

The windshield is glued on,then a rubber moulding is held in place by the glue.The plastic trim strip is held in place by clips under the rubber moulding.Just glue it back in.

yep, benign.

 

when they say "glued in" - this is not typical glue like you may be thinking.  you won't cut through this stuff with a knife.  whatever adhesive you put on will not get in the way at all of any future windshield replacement if necessary.