'Satellite' that seemed to behave in ways no man made machine could move.

After the fireworks on the 4th, we were at our residence watching for shooting stars.  At 6500' and a crystal clear sky, the view was breathtaking.  We watched a couple of satellites go over head, the first one faint and normal speed and the second one much brighter and faster (I'm not sure if it was the ISS but it was very bright for a satellite).  Both moved in straight lines directly over head.
 At this point, we noticed another 'satellite' following in the same flight path as the first two.  All of the sudden, it took a hard turn to the left (not 90 degrees but a fairly fast turn) went for a short distance, curved back to the right and continued  curving right and then left for several more turns a bit irradically (going straight for 1-4 seconds between turns).  The speed of the object didn't seem to change at all during the sighting as the turns were all fairly smooth.  By the time it went out of sight, it had veered off 45 degrees from it's original flight path.
 I'm certain that it wasn't either a low flying or high altitude air craft and at the elevation that satellites fly at, the G forces within this object must have been massive.
 I have another witness who watched the same thing I did.
 Sorry there isn't much more to the sighting than that but it freaked the both of us out as we couldn't think of any known explanation.  Is there any similar reports to this sighting and does it have a rational explanation?  thanks!