Default [Q] Gasket/Seal on motherboard

I purchased a replacement screen/LCD for my i535 on Ebay which was supposed to be OEM including pretty much all of the internals but unfortunately didn't come as pictured.
I removed everything from my old frame but noticed the new one didn't have the silicone type seal where the motherboard meets the frame.
Would anyone know if that material is some sort of a conductive seal where the motherboard surface meets? I probably shouldn't have but laid very fine lines of silicone where the factory "silicone" was supposed to be.
After assembly my signal is going up and down, searching, going to Verizon to Extended.
My question is would that seal have had something to do with the motherboard making a necessary connection to the frame for reception?

Thank you for any input.