Its common on floating discs, the bobbins eventually wear & its made worse if you have had a sticky calliper at any time. some people will tighten bobbins but its not something I feel comfortable doing I'd rather just get new discs but none of that cheap Chinese shite, you wouldn't believe the amount of chinky discs I have failed at really low mlilages
If there is enough movement for the tester to advise it then it WILL get worse & become unsafe sooner rather than later so I'm afraid you will have to bite the bullet & get some discs mate, check & clean the callipers out while you are there