Thank Joan and Kai.3ifor your replies,
No, I hadn't checked the gcode since I had no clue what code to look for
so thank you for expanding my very limited gcode vocabulary:-)
but after reading a post here about the same issue, Joseph had suggested it could be debris in the filament sensor.
I checked and blew it out, then realized the sensor always seemed pretty loose. I used 2 small pieces of folded paper to take up the slack behind the sensor and closed it.
Since doing that, it's an hour into printing flawlessly, so I think that the sensor moving around during the print was the cause, which would explain the very random frequency of the filament switches. It seems that the sensor moving sends a false filament out message and call for a filament change.
Thank you again for the help.
Unless I post otherwise the matter has been resolved and ( assuming it continues to work ) , please share this solution.