Is it because I made changes to these files (probably traces) that CVS did not dare delete them?
yes
But shouldn't it say 'was removed, no comparison available'?
well, it's hard to tell between a deleted file and a not yet submitted file (knowing that you can also recreate a file with the same name as one you've already deleted) so, an error message telling that a file with the same name exists in Attic would make more sense
anyway, it's a always a good point to inspect closely the output of a cvs update
A+