Still grinding rails on the Green Line?

Recently I saw the rail grinding equipment parked on the Blandford St. storage track on Comm. Ave. I thought the griding was all done a while ago, before the Type 8s were back in full service - but I guess I'm wrong.

Is there rail grinding still going on, and is it now a regular part of track maintenance?

Thanks!

Might it have something to do with the sinkhole on the B-line?

That's the only thing I could think of.