MacBook Pro Power Adapter Issues

Has anyone had to replace the 85 watt power adapter for the MacBook Pro due to cracking insulation tubing? My power adapter is only three years old and it looks like the tubing has become brittle after prolonged usage and fluctuations in heat caused by AC power (see photos). Quite frankly I don't understand why this is happening. I own other laptops (Toshiba and Gateway) much older than the MacBook Pro and their power adapters are in perfect condition. Perhaps Apple needs to take a look at the material being used during the manufacturing process. The replacement cost for this particular power adapter is over $100 and I'm wondering if the same cracking/splitting problems will occur again with this adapter after a couple of years.