I've been running a PrimaLuna ProLogue 8 CDP for quite a few years now and have yet to run across a noticeably warm disc but I usually change discs after each play maybe cutting back to a favorite track or two but even then I have never a noticeable a change in disc temperature when pulling it from the tray. One does have 6 vacuum tubes above the CD drive in the PrimaLuna CD players but even with that, it would take a direct heat source to even begin to disfigure a CD. Personally I wouldn't worry about it and just enjoy the music.
