I'll have to investigate. It looks like it's still updating the zoomed-in images, but zooming out to a point, it's not up to date anymore. So my guess is that the image-tiling script is having problems. Thanks for letting me know! These things usually hum along for years without intervention. Until it doesn't.
So it was more mundane than that. I added a CDN service to it roughly a week ago. Apparently it was a little over-aggressive in its caching. I've changed it to cache for no longer than 12 hours so that changes will be picked up the same day. We'll see how that goes. The whole CDN thing is a bit of an experiment.