"Start to rise" isn't very descriptive. Does it actually climb and continue to climb? How fast does it climb? How long does the climb continue? Did it stop climbing on its own, or did you have to command a descent?
One of the generous folks on...
On his cell phone, maybe. A small helicopter wouldn't have radar or other means of detecting a drone.
It's unlikely the pilot had any idea that you were there, unless he noticed a person on the cliff in the classic "two hands on the sticks...