If I remember right, tin whiskers were determined to be the cause in the crazy Toyota runaway accelerator pedals a few years back. I think it's mainly an issue with lead-free solders, which RoHS has forced into widespread usage over the last decade.
The problem was ultimately found to be a combination of pedals being pressed by floor mats, pedals sticking on their own, and drivers pressing the wrong pedal.
That's not to say acquiring non-RoHS components isn't made more difficult by RoHS.