Originally Posted by Sheldon Brown
My advice is to ride it. If it turns out to be a problem in practice, the problem will be a tendency of the headset to loosen up, not earthshaking nor life threatening. Only consider having more work done on this if the problem actually occurs.
My experience is that a loose headset can cause a front end shimmy which can lead to an accident. A loose headset will also lead to premature wear on the headset. I would recommend that if you do decide to ride it as it is, you should be very cautious.