So Air Force Space Command boss Gen. William Shelton gave us a tiny bit more insight into the service’s super secret space spycraft, the X-37B, when he said that it’s doing its super secret — and year-long — mission excellently and that there’s no need for a bigger version of it or to increase the size of the X-37B fleet.

What was really interesting about his comments, was the fact that he wouldn’t say just how big the fleet is. Keep in mind that the service has said that it’s got two of the mini-shuttles for a while now, but Shelton’s response to a question about the size of the fleet raised more questions than it answered.

“There’s no plan, certainly that we can afford, to increase the fleet size,” said Shelton during a breakfast with reporters in Washington this morning. When a reporter followed up to his statement by asking if the fleet size was just two vehicles, Shelton replied by saying, “let me check on whether or not I can talk about that.”

Weird, considering that the service has been very public about the fact that it has two of the space planes. His response seems to open the door to the possibility that there are more than just two X-37Bs.

Other than that, all Shelton would say about the robo-shuttle program is that “it is doing very well on-orbit and we don’t have an exact reentry date for it, it’s had a successful mission and we are very happy with the performance.”

He was discussing the record breaking flight of the second X-37B, dubbed Orbital Test Vehicle-2, that has been aloft for more than a year now. As for what it’s been doing for that year, we can only guess.

Update: We just heard from the Air Force, they maintain that there are only two X-37Bs and the next flight of OTV-1 is scheduled for the fall of 2012.