Futaba sais don't turn on Tx with antenna collapsed?!?
Just keep it reasonable guys. When you range check with your antenna collapsed, keep the test brief. If you are going to sit down with your Tx and play programmer for a while, extend it.
Don't read into it a big problem. I'd say, that if you kept your collapsed antenna range checks under 3 minutes, that you would never develop a problem. At least, that's the way that it has turned out for me over the last 42 years.
GeeBeeJim