Unknown erratic movement in a :30 second shutter photo.

I often go outside to shoot pictures of the stars, planets and Moon.  On March 9 it was very clear outside, so I went out to shoot some time-lapse images of the stars.  From 21:04 to 22:10 I shot about 33 photos, most at a :30 second shutter.  Upon review of the first photo of the night, and only the first photo, there is erratic movement in the sky during the :30 second shot.  This shot is pointing South by Southwest, and the unidentified object draws a bouncing line from point to point.  Maybe this is a common camera abnormality, but I am not familiar with it.  While the camera is stationary, and shows all the stars and trees in the background to be stationary, this object moved around the shot in the :30 second shutter time.  Of the other 30+ shots I took that night, I don’t see anything else like this, including the shots in the same direction that I took shortly after the first.  I hope you can tell me what this is? I can provide other images from that ! night, if you think it could help.