This will probably get merged into the consolidated .bomb issues thread, but I also had that error message come up for a few days.

I chalked it up to the fact that I had just bought a membership and perhaps the website wasn't smart enough to figure out that it was expiring in the same month of 2011, not 2010. It went away after a couple days so I hadn't thought about it since.

No issues with my membership to report either - used it just last weekend.