Hey Shrike
Is the play in the wheel (wheel bearings) or in the cush drive that holds the spocket (some play would be normal)?
If you're feeling play in the wheel bearings, or between the wheel and the axle, you likely have some worn parts, and you should dismantle and inspect. If the bearings are worn, you will want to replace them ASAP. If the axle is worn, you could have bearings starting to sieze.
You should check to verify.