Just bottled a hefeweizen beer that consisted of 6.6 lbs Wheat DME, 1 oz Hallertau hops, and Wyeast 3068. OG was 1.062, about what had been predicted. I had built a 3 L starter for the yeast (production date was in September, so while this seems like a large starter, I think mrmalty recommended something like a 9 L one based on the dating), and the beer sat in primary for 3 weeks before bottling. Active fermentation had started within 15 hours or so, and didn't stop bubbling in the airlock for a good 11-12 days.
So, I took a FG before bottling, and it was at 1.020, when it was supposed to be at 1.015 or thereabouts. This was only my second batch of beer; last batch the FG was a little high as well. Any suggestions as to what could have caused this? It was only a partial boil (3 gallons) topped up to 5 gallons; is it harder to hit the FG with partial boils?