What caused play in my freehub?
It is possible that the freehub has become loose from the hub. Remove the axle and bearings from the hub. Insert a the correct size allen wrench (I believe a10mm) into the non drive side. Tighten the retaining nut. If hub continues to spin you may need to use two wrenches. One inserted in the free hub  and one to tighten the retaining nut.