YES!
There should be a thin paper gasket under the bottom of the flange, but if there's a gap at all, the oil pump drive isn't lined up with the drive tang on the bottom of the distributor shaft. Make sure the drive gear is meshed with the camshaft in the proper place to get the firing order right, and tap the starter until the oil pump drive drops into place. Then set the ignition timing, and you're good to go.
Jerry