Yes, it is unusual and the
possible reason is:
http://www.pprune.org/rumours-news/5...-st-lucia.html
Could be that it was a member of that crew, who had given up their spare time to help the pax from their flight. They would then be out of their usual work/rest cycle and with the hotels all booked for Xmas the only way to get home. If no seats in the front of the plance, then that was the best option. I sit to be corrected.