[RF-82 rev.IV build quality]

Hi all, i found some good deal on used pair of RF82. My only concern is about build quality - in the pictures you can see like the outer layer is wrinkled at the edges. Is it normal, or could it be a sign of previous repairs/humidity? This defect is not visible when covers are on, but maybe someone can tell if it's normal thing or worth concern.

Thanks a lot!