Again, growth takes capital.
All of the MLPs should be going to the market. Yields are low, the market is "relatively" stable right now and any company that has expansion projects in 2012 and 2013 should be lining up to tap the equity markets for at least 50% of the total expansion cost. You have to strike while the iron is hot.
Companies like PAA with a strong coverage ratio can afford to raise equity a little sooner than necessary, even if it won't be fully deployed for 3-6 months.
Personally as a longterm unit holder, I am happy to see unit offerings because it means the company has secured the capital it needs to expand.