An R&D employee from Genelec already looked at this and said it's fine. I'm not a material scientist, and neither is anyone else in this thread I imagine, so worrying about how it looks in a photo seems totally ridiculous to me. If there was a problem, they would definitely want to correct it, and it's very unlikely anything broken is leaving their factory(compared to most) considering they test, measure, and tune the responses of each monitor individually.
The 8351B is the 2nd revision of a monitor released almost 7 years ago, if there were common woofer material problems then Genelec would have corrected them with this revision. They also have a very strong reputation for reliability in working studio environments to uphold. Looking at photos and saying 'wow that looks weird I wonder if the speakers will break' just seems like self-reinforcing anxiety with no factual basis.