This may sound nuts? But what if it was a private space program? Say the launch platform was a rented barge and the secrecy is proprietary. It would explain the NOTAM that is said to have gone out for the time of the launch, and the direction. Am I saying this is the only explanation? No. But it does make sense. If it was a test of ours, it would have been announced, and if it was a test of somebody else (the Chinese), they sure as hell wouldn't do it off our coast where Onizuka AFS, amongst other places, would get every bit of launch telemetry. Not to mention the escalatory elements....
In short, I can't say what the hell it was. Something tells me it was big, too big to be MANPADS, and anything bigger is going to attract attention...