Sorry but a couple questions and observations and apologize if these are obvious questions that you already took into account.
1. Are you using a hydrometer or refractometer to test specific gravity?
1a. Are you sure the hydrometer is accurate? Ie, did you measure water (distilled preferably) and get a reading extremely close to 1.000?
1b. If using a refractometer did you account for the alcohol variance. You probably know this but refractometers don't do well testing fluids with alcohol in them. But can be used accurately in an alcohol enviorment with some calibrations.
2. Were you working off a known recipe? And if so, were you above or below the expected pre-fermentation gravity?
Your ferm temp sounds good and to paraprhase the above post. There's a lot of yeast in that brew! Those guys just eat everything. Maybe there are not many fermentables in this cider, (sounds like there is quite a few though) I'd check (if you haven't already) on the testing tools and if they are working as advertised just keep our little buddies at a happy fermenting temp and forget about it for a month or two. I think the yeast were overwhelemed in a high specific gravity enviorment and are just getting themselves built up and ready to go eat some sugars, fart co2 and pee alcohol.
Disclaimer: I don't have a clue about Cider.