Sim, é possível que isso aconteça.
Acho que o Google diz melhor :
Please also know that the data we show can unfortunately change at any time in any direction. We generally have a very high accuracy rate, and we update our data as fast as anyone in the industry and faster than most. That said, these changes are determined by the airlines, and we do not know when or how the data will change. We're always working with the airlines to improve the quality of our search results, but it may be possible that a specific fare you see is no longer available.
If you're unable to book a particular flight at the price you saw on our website, please let us know.