I think the sudden jump just means a lot of stuff was added to the code. The system is automated. So it just does this “new code? -> Add building a new version to the queue”
This page: http://ci.narc.ro/view/Cataclysm-DDA/job/Cataclysm-Matrix/changes (thanks mugling) should give some more info on what has changed recently.
Also note that a lot of the builds have errors : http://prntscr.com/borkpp (the red dots). This means something went wrong. The system will then up the version number for the next build. The broken versions will not be distributed of course. That would be unfun.