First Yeast Starter - Getting Odd Results

Roughly 12 days ago I brewed my 8th batch (an IPA) and for the first time used a yeast starter (WLP001). My OG was 1.066 (right on target for my recipe). I fermented in my basement, roughly 65 degrees and vigorous fermentation started within 12 hours. Well, here we are 12 days later and I'm still getting a bubble in the airlock every 30 seconds. I took a hydrometer reading but it was only 1.020 (recipe states that it should drop to around 1.012).

So, I guess I'm bewildered....this is the longest any of my beers have ever fermented, yet it still isn't close to dropping to the hopeful FG. I just figured that using a starter would get me to my FG faster. I guess as long as it's still bubbling, just let it go, right? Are there any problems with my fermentation taking this long?

Thanks!

A copy and paste from the White Labs site:

I am toward the end of a recent brew (bottle conditioning phase) and had a question about WLP001 California Ale Yeast. O.G. was 1.07 and I wanted about a 1.017 FG (76% atten) but I only got to 1.024 (65% atten). I want to try the recipe with the California again soon, and am wondering what I should do differently to get the attenuation to about 76%.

The issue may be with the fermentation itself or with the available sugars present to the yeast. Even though your mash schedule may seem correct, try dropping everything in your system 10 degrees Fahrenheit. That is where you would start to see if your wort becomes fermentable.

You could also try different base malt. For fermentation, make sure you pitch the yeast between 70-75F, then drop to a different temperature if you like after fermentation begins. Keep the temperature consistent during fermentation, even fluctuations during the evening can stall the yeast. Proper aeration at the beginning of fermentation will also be helpful. This is one thing that separates homebrewers and commercial breweries, commercial breweries have almost no problems with stuck fermentations because they have tight temperature control and they saturate the wort with oxygen before they pitch the yeast. One way to get more oxygen into the fermentor is to use a fish type of aquarium pump. Put an air filter on that you can get at homebrew shops, and turn on for one hour after pitching. Don’t use a stone, it will foam too much, just a small bore tubing, this will add big enough bubbles to mix things up, and you get good oxygen delivery into the wort. An additional tip is to transfer the beer when it gets to 1.025; the transfer itself helps to add a little oxygen and mix things up.

As the latter part of the quote suggests, it seems a transfer to a secondary would be your best bet; it may help in adding some additional oxygen.