Actually, according to the producers of the show at Paleyfest, they strongly hinted that they would like the huntsman to make another appearance in FTL.
We haven’t seen the last of Sidney Glass or Sheriff Graham. Not only does the man in the mirror have an arc before season’s end, but the Huntsman, series co-creator Edward Kitsis reminded fans, “is still very much alive in fairy tale world.” http://www.tvline.com/2012/03/once-upon-a-time-spoilers-paleyfest/
He could very well feature in a scene that happened in the past. The huntsman released Snow White in ep. 7 in FTL. This week’s show, episode 15, happens immediately after Snow White is released by the huntsman. Since the FTL events are all flashbacks, the huntsman is still alive there and could feature in such a flashback.
"That’s how you know you’ve really got a home. When you leave it, there’s this feeling that you can’t shake. You just miss it." Neal Cassidy