I entered a few corrections near Geronimo, Arizona, because I drove through the intersection of Geronimo Lane and Black Lane and it was a little bit different from what the map showed. When I closed JOSM, selecting the Perform Changes button, JOSM appeared to hang with the message "Preparing layer xxx for upload." showing on the dialog window. It appears that the changes were successfully uploaded. I will check in a day or two to see that my changes are intact. Note that I updated my Java version today (Oct 26, 2014) before running JOSM.
I should mention that I'm using Windows 7, 64-bit