I wonder, how do we know if it's a bug or a feature?
It happend to me once and I believe I was at fault myself. The reason is simple, the car lacks an off switch so when you exit the car it's so easy to lean on the window button, especially the button for the right rear window, and it just opens a couple of inches.
I'm pretty sure it's not a software bug. Without security camera footage showing the window lowering without any user input, I won't be convinced by claims like "I didn't press it."
A simple solution would be to disable the window controls when the door is open, or to give an audible warning when you lock the door with any windows ajar, in a similar fashion as when a door is still open.