In the next release (0.3.13), I'm going to change the format of the internal version number integer from 313 to 31300, for instance 31305 = 0.3.13.5. The last number represents changes on the SVN between releases and ought to be properly represented in the version number. Otherwise, it would be a pain if we had a mistake or something in one of the sub versions that needed to be worked around.
Thanks for the heads up. I'm actually checking version on my web apps, to assert if backupwallet is available, but as my private version is now widespread, it should be very simple to cope with that change.