I used to see this in vanilla when I had a large "fleet" which included multiple capital ships and it wasn't limited to the Vasari for me. I'll see if I can recreate it.
UPDATE: I was playing around with this and could not duplicate the situation yet. Though when I had view of a Pirate system and the next pirate "wave" spawned, they did something similar. The pirate ships all formed together very clutered and a couple made micro jumps away but it was in a pinkish/redish color. They then formed up and began jumping away normally with the normal color associated with jumps.
