My previous boat had a CDI furler, and the boat's jib halyard was not used. Instead, the sail was hoisted with a relatively thin line (maybe 1/4") that I believe had the core removed from it to make it flatter. This line, instead of going from the head, through a block, and down to the bottom of the mast, instead was contained within the furling foil, was tied off at the furler drum, and was only a little longer than the forestay (so, in other words, there's no extra line present when the sail is up).
Lowering the sail involved tying a messenger line to this "halyard", so that when the sail came down (and the end of the halyard went up) you'd still have a way to re-hoist it.
If this is the case with your furler, perhaps this mini-halyard came undone and the end has worked its way up the foil a foot or so?
--Michael