Using an infrared transmitter and receiver mounted on the controller circuit board, the tub home sensor detects when the tub is closed and ready to start a cycle. The transmitter sends infrared light through an optical light pipe to the side of the tub. Another optical light pipe leads from the infrared receiver to the side of the tub. When the tub is closed, the two light pipes are optically connected via a prism mounted in the side of the chassis. It's easier to check the machine when it's pulled out from its installation.
I know you guys are trying to be helpful but the answer is wrong. I have the same unit and mine does the same thing. The door physically pops open just slightly, like a spring lost its strength. Stay tuned I'll figure it out and post as solution.
Actually it the one or both the slide mechanism on the drawer is attached to. Whirlpool part number WP99003759 for my case, broken spring. Not cheap at $90-$120 Odd that on both drawers it was the left side.