Horizon at the Fountain -- Why so Blurry??

So this is the third album in a row that my Horizon shots have been noticeably blurry. It kind of seems like the lens isn't in focus, although that doesn't make sense in a fixed lens fixed focus camera. I mean, I understand the stuff near the lens not being in focus at wider apertures, but infinity should always be sharp (my earlier albums, that was always true). Interestingly, the vertical panorama shots seem sharper in some cases -- could the lens just be loose? It's under warranty so I'll probably just need to send it in, but any suggestions are welcome!

More photos by russheath