The flight attendant must have been blind - the lady is not even overweight at all, let alone looking like being pregnant, so it is well and truly a gaffe by the flight attendant. Here is an article from yesterday's Christchurch Press which has a photo of the lady concerned - as to how the FA could come to the conclusion that he did, I'm at a loss to know:
Woman mortified over Jetstar pregnancy query | Stuff.co.nz