If I remember correctly (which probably isn't the case haha) I think a few years ago when Gretna won the title, they were a lower seed. It was after the playoffs had expanded. They would not have made the playoffs in the old format, in the 2nd or 3rd round dont remember which, they had to come up this way to Riverheads, so they were lower seed than them.
It looks like from MaxPreps archives, that they were probably a 5 seed, I could be wrong but it looks like their 2nd round game against Giles was at Giles, meaning they would have been lower seed, and then of course Riverheads who was 1 seed