I'm wondering that too. The thing that throws me off on that though is that Lockdown's reveal is presumably when he shoots Optimus with his gun-face, and a scene in the trailer shows Optimus talking to Cade with Hound & Crosshairs in the shot, and I'm pretty sure that that scene takes place before that. I do like the theory though, maybe we don't see Lockdown when Drift breaks the 'bots out of Lockdowns ship, then we see a full shot of him later in Texas where he captures Optimus and such. Who knows,we have less that a month till the movie releases!
(my only complaint is the lack of size difference between prime and Lockdown....they look about the same in the trailer