This came up in a game a few weeks back, and it's been bugging me. My T-65 with BB-8 was on a rock. I wanted to reveal a green, BB-8 off the rock, then move. My opponent predicted what I was going to do, and pre-emptively told me it was against the rules.
I didn't query the point, and played on, but thinking about it afterwards I just can't see why it would be against the rules. The template wouldn't have crossed over the rock, the action isn't happening in the action phase, and unless it's been specified by a FAQ somewhere, I don't get it.
Do what's the story here?