New house ( 4 months old) with 5' fiberglass shower with glass sliding doors in master bath. Drywall in shower wall surround above shower and ceilng in shower is fine. On each end of shower outside of shower doors is about a 6" wide section of drywall from floor to ceiling is slightly off color and sticky, but is completely dry. Builder has no idea why. Rest of bathroom drywall is also fine. Builder's painter looked at it and has no answer. Any suggestions would be appreicated.

Masking tape residue from the shower rail install?

Overspray of adhesive? I'd bet they used spray adhesive on the shower wall panels to adhere them to the walls.