Does this happen with every print of this model, or any model, or did it happen just this one time? Whatever you do don't touch any of the x/y motors while a print is underway. If you do this the prints will shift every time due to the change in resistance. I had this happen quite a bit until I learned to just not touch the motors mid print.. Another thing to check on is if the y motor is super hot when the shifting occurs. You might need to turn down the power on the stepper driver just a tad. Could be getting too hot over time, not immediately out of the gate, and then causing the shifting. I installed a heated bed on mine and noticed that the heat from the bed was causing the motor to overheat and shift so I ended up putting a small fan on the motor and haven't had a problem since. Thats a bit different but I thought I'd share.