Hi Coppz,
I think I've just been unlucky, I wouldn't worry too much.
I've not had her too long and there was quite a build up of dirt in the lip behind the arch, which probably contributed towards this bubble!
I must admit, I do a lot of shedding too, so the Zed will spend most of the winter in the garage, especially if the gritters have been out.
To be honest if the weather was bad I probably wouldn't get out of the street, had a good laugh at a TT last year that couldn't get up the slope!
By undersealed, do you mean wax oil?
Definitely worth getting the bubble fixed and then the car treated, don't want it to slowy rot away on the drive!
Cheers
Jacko