2002 Toyota Sequoia automatic door locks

I have a 2002 Toyota Sequoia with factory installed automatic door locks and anti-theft system, and an after-market AutoMate Keyless Entry System. Recently, the doors keep trying to lock over and over while driving (even though they are already locked.) The doors do unlock normally as soon as the vehicle is put into Park, but will lock back sometimes when the door is still open and sometimes after we have exited the vehicle.