While nothing has been confirmed just yet, it's being reported by PWInsider.com that Mark Henry might have injured himself at a house show last night in Boston, Massachusetts.
Apparently he hurt himself while running down to the ring for a save and it took a while for him to stand up and he looked like he was in pain. From the accounts it looked as though he may have hurt his knee.
Henry does have a history of hurting his knees in such a manner. One time he hurt his knee while delivering a running splash in the corner. This was a few years back. And in late 2011/early 2012 his knee gave out while simply throwing a punch at The Big Show during a match on SmackDown.