Not lucky, but skilful.
What he said. Banding is always a potential issue under fluorescent lights, even with an ordinary shutter. The way to avoid it is to ensure that the exposure time is an integer multiple of twice the mains frequency. So in the UK with 50Hz electricity, shoot at 1/100th, 1/50th, 1/25th, etc and you'll be fine.
(Some modern DSLRs have an anti-flicker setting which is supposed to avoid this issue without forcing you to choose a special shutter speed, but I don't know how it works or how well it works.)