Check the last SEC filing. DBRG has been buying preferred in the open market over the last several quarters.
With the I yielding a tich more than the others and trading in good volume, it's the natural for first to be called.
Notice how the price has been ramping up and today - good volume and constantly higher.
I'm not anxious to lose it - great yield at my cost, but I'd take the CG from a call quite happily.