I feel like they did that a couple times in the G1 comic (Soundwave in a locker at an oil rig comes to mind). I know liberties are taken with mass shifting already but for some reason I'm just not onboard with large size changes in the movies. I'm fine with it in other mediums for some reason, but I can't quite put my finger on why it irks me in theory in live-action. Maybe it messes with my ability to suspend disbelief at the robits being grounded in the real world? I don't know.