Oh please. The electors are party insiders, they will not be interested in looking into any closets or under any rugs. (Although one pledged to McCain might just have slipped past the "bipartisan" filter of the McCain Campain staff, who would stand up and try to get the information, but it's not clear that even she/he would have standing).
Now that might be different if the information gets into the public domain by other means. Lawsuits are still in play, but I don't hold out much hope for them.
McCain would presumably have had standing to sue to get the information released, but it's now too late for that.