Other mREIT haven't offered SPO since July of 2012.
SPO, if offered, won't occur until after ex-dividend 3/xx/13 and at higher share price (above 33) IMO.
AGNC might finally be out of the doghouse since 11/2012 with yesterday's positive comments.
They wouldn't SPO between a div announcement and ex-div (I'd be willing to sue them for pump-and-dump if they did), but they sure could SPO before they announce. Announcement isn't due for over a month.
But you have to assume they find this level of price relative to BV to be sufficient. They still need to pay the underwriters and give a discount to the market in a SPO, so it should have to run another few % upwards to give them a comfortable buffer.
They also need to see a reason to have the cash to buy the MBS.
If you could get those two things, and if they haven't annouced the div, then the SPO could be called imminent.