I know the limits have not changed and in my 360 from home tool, it says I completed 329 sectors, while yesterday it said 330. I also know which degree sector it is that changed from green/complete to red/incomplete.
I have not changed my home coordinates, otherwise more sectors would have changed.
I'm pretty sure it's related to a found cache, probably the only one I had in that sector, but I am unable to find which cache it was.