what is it.
 

I'll get a pic tonight, but while I had the top down, I was applying leather conditioner and there was a rectangular looking screen mesh on the passenger B pillar covering. It is about 1 x 2 inches. Any ideas?

It's the airbag occupancy sensor.

Take a look at Sam's video about 4:30.

Most likely one of the ultrasonic sensors for the passenger airbag. There should be a similar looking mesh on the passenger A-pillar and the overhead console.

This rectangular one is on the B pillar, behind the front seat.

pic, so this must be used in conjuction with the A pillar one to confirm a pax present.