Hmmmm.... Could you borrow a different one to try? Because it very likely may be not a girth, but the attitude. My qh always tries to nip the person holding her while I tie the girth (she's not trying to do it on me though). If she's busy sometime she "forgets" she wants to nip, but if she's not busy she may look for the chance (even though she's disciplined every time).
My paint has sensitive skin, but I never had issues with my Pro Choice (which is neoprene and kinda "rubbish" (not smooth) on side that goes on belly).
"Life isn't about waiting for the storm to pass: it's about learning to dance in the rain..."
"When we are no longer able to change a situation - we are challenged to change ourselves."
"How people treat you is their karma; how you react is yours."