False readings happen all the time, you will probably be okay. Did you remeasure your final cooled volume to see how much you actually have left? I got a lesson about propane tanks a few days ago, I had my regulator set at a particular place to have decent boil times, but not boil overs. The tank was getting low, the flame was going down, I reset the regulator, I then changed to a full tank w/o resetting the regulator, and I went from 7.5 to 4.5 gallons before it dawned on me what my error was.
Aging from last year: Hard Cider, Triple Chocolate Stout, American Amber II
First fermenter: American Mild
Second fermenter: Empty
Long term aging: Strong Scottish Ale, American Stout
3 new hard ciders, first is a Apple Raspberry, second will be a Apple Grape, and third Apple Cranberry. These will all become Jacked Ciders