Same thing happened to my front window. It started as a small chip then spread. Only mine is in the center of the windows (annoying!). This happened right before the summer but I havn't had the time, money, or desire to have it fixed. Luckily mine has stopped moving. currently it's about 18-20 inches long. A few people that i've talked to said it can be fixed but no one seems to know where. ;(

-Greg