Originally Posted by jtejedor
+1 make sure to double check whatever you are using to test gravity. I use my refractometer to test gravity while the beer is fermenting/finished and usually using spreadsheet adjustments it is usually pretty accurate. I freaked out because it said my beer was way low (1.004) and I feared infection also. Used my finishing hydrometer the actual reading was at 1.016. So yeah either way if you get a reading that seems way out of whack double check the hydrometer or refractometer. Just going by taste might not be a good indicator. I too am paranoid and have had batches I thought were infected because they tasted "off" after kegging. Usually the beers improve drastically after a month or two so the beer might just be green.
Maybe you know this already, but a refractometer is not particularly accurate in getting you an FG. Even with the necessary adjustments to account for the presence of EtOH. You're better off just using your hydrometer for FG readings.