^ that, or the return spring could have broken somehow. I've never actually seen that happen before, though, save for carburetor systems
And for the odd story, a guy in the shop I used to work in had a mouse blocking the throttle plate on an older honda he worked on. Apparently it was making a nest in the airbox, and ate a hole in the filter, eventually getting sucked into the intake and jammed open the throttle body. Good thing the guy that drove it in didnt floor it, heh...that'd have been an awful smell, and probably taken a lot of work to fix.