Cup steering wheel bubbling?

I know FF197/200s are well known for melting steering wheels, but I've never read of anyone with a Cup with the standard Dynamique style leather wheel having any issues, it's just my Cup steering wheel is wrecked, it's not melted but more bubbled up, it now feels as rough as sand paper to the touch, all the way around.

the cars a Sept 2009 59 plate, bought it April 12 with 18K on if and I'm certain it was perfect steering wheel wise, it's now 16 months later on 36K, can't work out how it's stayed perfect for the first 2 and a half years of its life but has gone from that to totally wrecked in such a short time, it originally started at the 1 o clock area and it was just there for ages, now it's all round, at first I thought it was sweat as my hands sweat quite bad, but it seems to get worse every time it's a hot day/suns out, even if I park in the shade.

so is it common on Cup/standard Clio wheels as well as the chunkier 197/200 FF wheels?