If you're using slotted (concrete) posts rather than nailing to wooden ones then make sure that when you move the sides in, they're not too wide to fit the slot (which can happen depending where the new edge is in the case of featherboard panels)
The guy putting in the fence for next door had a chippie cut some panels down for him some days before, I wound up spending an hour or so helping him get the last short panel back to size with a plane and spoke shave (on account of it being pretty near, but not near enough, and having a bunch of nailheads stuck in..)