I've had my MBP for a few months and the plastic coating of the power adaptor cable has already melted/worn-through just below the magsafe plug. There is exposed wiring and the surrounded plastic feels warm. Is this covered under warranty? I had to replace my Powerbook adaptor three times due to similar problems (is the cable made of butter?) and thought the magsafe design was meant to resolve this? I've never had such problems with other laptops.