Check in version issue

A file was at 1/1 in the file system and on my computer. I checked it out, made changes to the assembly, added a configuration, and checked it back in. The version was at 2/1 before I checked it in and stayed at 2/1 after check in. I then checked it out and then immediately back in and the version went to 1/1. I opened the file and all of my changes were still there, even though the version is now 1/1.