I've had GE for 7 years. No interview required at renewal.
Four flights ago (this was AMS-SFO), I got SSSS.
Never happened before, hasn't happened since. It's random.
And in AMS at least, it was no big deal. Took 3-5 minutes.
Amusing anecdote, the lady waiting for secondary behind me told me when she OLCI'd she thought the esses meant she was going to get an upgrade!