Keith Olbermann has worked 13 days this month, leaving Countdown to be guest-hosted by Lawrence O'Donnell or David Shuster on eight nonconsecutive nights. This is after a two-and-a-half week vacation in July. He's back tonight, and MSNBC says he'll explain.

The last time Olbermann took a sudden, unexplained absence from the show, it turned out to have been a hissy-fit work stoppage after Rachel Maddow booked Ben Affleck and MSNBC brass refused to back Olbermann's attempt to bigfoot her and steal the interview. After CityFile reported on the flap, Olbermann blamed the absence on his mother's death, which had occurred two weeks prior.

We asked an MSNBC publicist where Olbermann has been and, she responded: "He's going to discuss it on the show tonight, he's back tonight."

There could obviously be a variety of interesting and non-interesting explanations for the days off, which he took on the 11th, 14th, 18th, 22nd, 23rd, 25th, 28th, and 29th of September, and we're just wondering, is all.

UPDATE: A tipster sent in the screengrab below from Saturday's Red Sox game at Yankee Stadium. We posted it, saying Olbermann was at the game, because that looks exactly like Keith Olbermann. But we have it on good authority that it is not, in fact, Keith Olbermann. Our corporate brothers at Deadspin got the same image from the same tipster earlier this week, and didn't use it. We knew that. What we didn't know was that Deadspin checked with Olbermann to confirm that it was him, and found that it was not. We should have checked, too, although we didn't think to because doesn't that look exactly like Keith Olbermann? Down to the glasses?