Westbound CSX freight, drops cars at East Yard, then power leaves EB light?

After waiting nearly 25 minutes, I watched a Westbound train which had a yellow indication on the westbound signal, come out of East Yard Plymouth, Michigan, cross the diamonds of the North-South tracks, then come to a stop. Then it backed up into East Yard, and set out 52 cars. Then it was given a yellow signal again on the Westbound track, then cleared to Green. But instead of the train coming West, the power came out of East Yard, crossed over to the E-W main, but run East toward Detroit???
Never seen anything like this before, and the dispatcher, dropped the Westbound signal back to red!