[racket] Racket on Ubuntu 12.04

Just a sanity-check question, no cause for concern...

Has anyone seen strange behavior with Racket on Ubuntu 12.04?

I have some code and data that reportedly runs fine on an older version 
of Ubuntu (which will take a while for me to verify), but that that at 
some point has an incorrect Racket value internally when run under 
Ubuntu 12.04.  (In this case, Racket is 5.2.1 with CGC collector on x86 
32-bit, and there is an old-style CGC C extension involved, which has 
worked on multiple platforms for many years under heavy loads.)

I suspect there is a simpler explanation (i.e., a recent application 
code change that does not actually run anywhere), but while I wait for 
verification, I thought I might as well sanity-check possible Ubuntu 
12.04 problems, however unlikely.

Thanks,
Neil V.