I have been caught very much off guard by different batches of paper. If a print really meant a lot to me (as yours do - being for a show), I would eliminate any variables I have control over. This may just be a bad experience speaking - but it was Ilford paper, although admittedly, of quite a different age.
Of course - with a full size "final" test print on the same stock, this issue deminishes in importance, so this is more a case of "yes, it can happen" rather than "don't ever do that!"
Best of luck,
Peter.