Ok the car is a celica gt4 st205

I've replaced the rear diff mount that sits behind the diff,

Whilst removing this I have notice that the U peice that goes over the diff and bolts to the sub frame had a little play in it (front to rear) is this normal ?

When I bolted new rear mount on it stopped the play , is this play the reason that I needed to change the rear mount in the first place ?

Any Info would be appreciated