Hi Bill,
My venerable 350D has mirror lock up so I suspect the 1000D will have. (buried in the setup menu,first press of the shutter moves the mirror,second press operates the shutter). It depends on focal length of course but the vibration was very obvious at 300mm fl when I forgot to enable it. Though so as you say unlikely to be the cause here unless the meteor was right at the beginning of the exposure.
Robin