This is not necessarily a sign of imminent failure, more a matter of concern. Worst case, I believe would be some structural failure of the fork tips, so just to be sure take the wheel off and pull, push and twist and closely examine the fork ends and blades. Not likely but check. Hubs come in sealed bearing and loose/caged ball bearing varieties. Next look at the hub and check for obvious structural anomalies like cracked housing, loose spokes (it would be a lot of spokes for this to happen) etc. This is also unlikely.
Finally look at the axle/hub complex. Loose bearing hubs have a threaded hollow tube that is the actual axle and is 10x1mm threaded through which the QR slides. Check the threaded ends for looseness or side to side wobble, should be tight. If not then there are two threaded 'nuts' on each side that may just be loose. Or the bearings and races may be damaged. Some dissassembly required. See
www.parktool.com and click "Repair Help" at the top right and scroll down to the stylized bike and mouse over the front hub for a pictorial essay on this. If the bearings are sealed dissassembly is more complex. One other thing that can happen in addition to bearing laxity is a broken axle. Axles are easily replaced if loose bearing threaded type, but dicey if sealed bearing type. You will have to inquire at a full service LBS depending on the hub.
Steve