From a 737NG manual
Any of the following conditions or actions disengages the A/T
- Moving the A/T arm switch to OFF
- Pushing either A/T disengage switch
- An A/T system fault is detected
- Two seconds have elapsed since landing touchdown
- Thrust levers have become seperated more than 10 degrees during a dual channel approach after flare armed in annunciated
- Significant thrust difference along with control wheel roll input of 10 degrees or more, and flap position up through 10.
It sounds like the last case is what you are looking for.