I haven't heard about this, it sounds similar to the alleged following of the Apollo 11 astronauts to the moon. And the observing of the Astronauts on the moon as they got out onto the lunar surface. There have also been many reported sightings of UFOs at the location of nuclear bomb test sights. It seems that when we have new technology on show for the first time, the aliens are interested to see for themselves what it is. Bearing in mind the very high speed of Concord it doesn't surprise me at all that Aliens wanted to observe and follow it for a while.
Richard D. Hall, www.richplanet.net