http://www.acmoc.org/ACMOC_BB/showthread.php?t=4139
Lots of the D318 heads seep along the sides. Recommendation is to seal the gasket with a brush on sealer instead of relying on the ferrules and packings to seal it.
Wouldn't hurt to do it, you would loosen each bolt in turn and retorque. If you found any that would move without loosening them first after having been properly torqued the first time, I would be surprised.
I would also be surprised if it stopped the seeping.