I had a Terran small fleet consisting of:
1) a cargo hull with fleet warp bubble III
2) a transport ship with 1 Billion happy colonists/troops on it
3) a Colony ship with 500 hardy colonists on it

They entered the space of a heavy gravity planet I wanted to colonize (and had the required tech to do so). The colony ship deposited its colonists and the other two ships remained in the square adjacent to the planet, but lo and behold the graphics showed the colony ship as still with the fleet! If I selected the fleet the details correctly showed the fleet as being only the two warp ship and the transport, but on the main display all three ships appeared. This graphic persisted over several turns, until I saved and reloaded the game.

My save prior to the establishment of the colony was too far back and I didn't want to go back to it to see if the problem would reoccur. So I thought I would let you know.