Apparently, there is an issue with auto focus for X10s that have an “A” in their serial numbers. They can just stop focusing, as was reported today on the Fuji Talk Forum. This would be an inconvenience for most people :-)
If you have such a camera, be aware that if it stops focusing, you will need to send it to Fuji. You might consider calling them to ask if you can send it during a convenient downtime period before it fails.