Hard cider is VERY prone to film yeasts. These are spoilage yeast and are more bothersome in cider (with low acid and high pH values) over wine.
Did you use any SO2? By that, I mean campden tablets, KMBS (Potassium Metabisulfite).
Often it is best to adjust the acid up a bit with Malic B4 starting to ferment. This will add more crispness to the cider and lower the pH making it easier to keep from going bad.
Cider does NOT need to cellar for very long, just until it is finished. We test ours with clinitest sugar tablets (for sugars in urine) by Bayer labs. If you can find some. GET SOME. Bayer has recently discontinued making the clinitest tablets and we bought a bunch of bottles for that reason. 5 drops of wine/cider in small tube. Then 10 drops of water and then add 1 tablet. If it is BLUE = 0.0% GREEN is 0.25, and Green (lighter, more toward yellow) means 0.5% which is acceptable for dry.