"David Bash" wrote in message
My question is: is this all in my head? Can CD damage due to
excessive
heat manifest as a loss of fidelity?

Certainly.

However, for pressed CDs the temperature required should result
in visible warpage of the CD.

For CD-R and CD-R/W it is assumed the temperature threshold is
lower. However, I have CDRs that have stayed in my car (southern
US) since 1992. A couple of years ago I ripped a couple to my
hard drive and compared to the original WAV files. They were
identical bit for bit.

In the late '90s we took a bunch of CD, CDR, and CDRW and put
them in a lab oven at 70C (158F) for two weeks solid with no ill
effects (bit for bit analysis). We then increased the
temperature to find the point were audible errors were observed
(not just bit for bit). I don't recall the exact temp but it was
past the point where visible warpage was first noted. All three
types seemed to fail around the same point. However, the study
was not scientific so don't take this as anything other than
anecdotal evidence...and I wouldn't try to extrapolate to long
term reliability based on two weeks of data.