The trick will be if they try to claim it is 'wear and tear' - my 5yo i30 steering wheel 'leather' has worn... and was like that from about 4th year... but it was never peeling off (e.g. visibly lifted edge or pieces covering hands after driving). Peeling seems to indicate the bonding isn't proper or something has affected it (my sweaty paws didn't seem to have any effect on mine
). So you might need to politely argue the point - and you might still get told no.
The service centre I go to - indicated that any internal trim (so I would take it any door, steering and other coverings are the same) is covered by the full 5y warranty (other than what is obviously wear/user damage). A number of pieces of chrome trim were warranty replaced in mine - due to them peeling; they also, quite nicely so I thought, replaced (weeks before warranty end) the drives seat-belt latch/stork when buckle stopped springing up a little when unlatched (i.e. if you let the button go it would lock again) - which I had considered wear. But, again, it would depend on your service center and/or their warranty assessor.
