Audi TT roadster seats

I have a 2001 Audi Roadster. THis weekend, the passenger window was left open during a South Florida rainstorm. I discovered this immediately after the storm and dried off the seats. A couple of days after this event occurred, the passenger seat looks as though it is starting to deteriorate. I can't imagine a little rain caused a leather seat (it this is truly leather) this. I have never seen leather do this. Any one else have this problem. I have applied conditioners to the seat with no improvement.