Wanted to add to this topic by saying that my 2012 Focus with dual-clutch transmission (build date December 2012) also started to shudder and hesitate upon acceleration while going into 2nd gear. This started after 10,000 miles. It only did this on a warm engine (after several starts and stops). It was fine when shifting into higher gears.
Turns out that the clutch was defective. It wasn't releasing correctly. My Ford dealer called the Ford service hotline and they confirmed that this is an identified problem on some Focuses. Replacing the clutch was the only solution. They got a new clutch kit from Ford and completed the repairs in a day.
Just got my Focus back today and the problem is resolved.