Robot vacuum exhibits OCD behavior

I’ve had my vacuum for almost three months. It took a month for the software to get to the point where it was useful, but I’ve been enjoying my robot since then. I does a good job keeping the floors clean in between my more thorough cleanings. But today it did something strange. I told it to clean two rooms, and it did so, eventually finishing (I thought) and going back to the charger. After a while, it started again. I checked the map, and it appeared that it had cleaned both rooms completely, and had even cleaned a small area just over the virtual border of a third room. But it went to one of the two rooms it had cleaned already and just went over and over a small area, then slowly moved around to another area, and after spending some time there, went back to the first area and started moving over and over it again. I finally paused it and told it to stop cleaning, at which time it went back to the charger. (Good robot!) Has anybody else experienced this type of OCD behavior? Is there any reason why the robot would try to clean an area over and over again during the same cleaning cycle?