Kawasaki Cars on a Fitchburg Line Siding

I saw something odd today. I was at the Fresh Pond Mall (near Alewife), and noticed that there were some K-Cars that were stopped over on the commuter rail. I soon realized that they were on one of the sidings off the Fitchburg Line. I wonder what they were doing up there, because its been awhile since any K-Cars have been spotted up north, other than the Halloween Train.

These cars had no engine attached, and one of them was car 914.

Any info about why they'd be on the Fitchburg Line? Were they just re-shuffling?

See this thread. I feel a merge coming on