Swivel hubs leaking - how urgent?

[MudRunnerTD]

I would have no hesitation using 4wd with a leak that minor. If you are really concerned and you want piece of mind then roll under the front of your car with your 1/2" breaker bar and undo the filler nut to the front diff and stick your finger in. If your fluid is up near the top then drive on mate. If it's a little low then add some diff oil if you have it. You will dump it all out anyway. You would be weary about using 4wd only if your front diff was empty and dry.