[Lost81]

"...in early DVDs. The glue that holds the layers together can lose its grip, making the disc unreadable at least in parts. Users that bend a DVD to remove it from a hard-gripping case are practically begging for this problem, because flexing the disc puts strain on the glue."

http://www.cnn.com/2004/TECH/ptech/05/06/disc.rot.ap/index.html

-Lost81

[Rob Babcock]

I've been harping on some of these types of issues, but I haven't really managed to start much of a panic!     I've not had any problems like you're describing, though.