too low fg, infection?

So I have a Liberty Ale clone that's been fermenting for 2 weeks at 68 degrees. The yeast used was american ale from wyeast and I made a two liter starter. When I brewed this beer, I was running out of propane and the second half of the boil wasnt as vigorous as i usually like it and the flame went out 5 min early. Anyway, i was about 5 points shy of my target OG. I just racked yesterday into a carboy to dry hop it, and when i checked the gravity, it read 1.002. The target was 1.012, so i immediately suspected infection. I tasted and smelled the sample, and I cant really detect infection. It does not smell vinegary or taste sour at all, and is actually a little sweet. Any idea what is going on?

I would check my hydrometer calibration first.

seems to be calibrated, reads 1.000 in tap water

Just as Info :

Everytime I had an infected Beer , I had a high F.G. and the

Attenuation was around 50% .

Hector

I use Wyeast 1968 exclusively. Somewhere on here there is a discussion about Wyeast 1968 and attenuation. Once in a blue moon I get a final gravity like you and I always just thought I was making a mistake somewhere along the line. In that discussion other people also get a ultra low final gravity once in a while. Seems like for whatever reason the yeast really made themselves at home and did a little extra work. Was this an extract brew? If it was all grain you may want to check the calibration of your thermometer during mashing.