I had the same problem yesterday afternoon...
The window on the passenger side only was halfway down when I returned to the car park after leaving it locked with windows closed.
The driver's side window was still closed fully, and the car had been left for about an hour. The windows had not been opened at all since driving out of my garage that morning.
UK spec car less than 1,000 miles to date.
Going into the dealers next week anyway for warranty work, so the dealer should be looking at this also.
Has anybody had similar window problems recently? If so was have the dealer done to sort it out?