Play in t type derailleur mounting

Hi all, 

I've got a t type gx axs derailuer of my trek fuel exe, it's been fine for a couple of years, but recently I've noticed it ghost shifting when under high load, ie cranking hard on the pedals in a middle ish gear.

I've had a look and with the wheel fitted and bolted in place there is a tiny amount of play between the deraileur and the bolt that bolts it to the frame. 

I've had a look on the Internet and you can buy a new mounting kit, as below

https://www.tradeinn.com/bikeinn/en/sram-x0-t-type-eagle-axs-rear-derailleur-hardware-kit/139580527/p?utm_source=google_products&utm_medium=merchant&id_producte=18677606&country=uk&gad_source=1&gad_campaignid=19775635674

So I presume these parts are known to wear. Just wondering if anyone else has seen similar and what fixed it for you.

It Would also be good if anyone else with a t type could see if you can detect any play where the mech mounts to the frame, you need to test for it with the wheel in place, because it's only with the wheel in place that everything gets tightened down properly. It's only a small amount of play but is obvious if you grab the mech at the top where it bolts to the frame and give it a wiggle. 

I can't feel any other obvious play anywhere.