Kohler V-Twin oil leak at breather cover

After rebuilding this CH20s engine, at startup, there was a significant oil seep from the edge of the oil breather cover. During the rebuilding, all surfaces were cleaned and wiped with lacquer thinner, and a new gasket, reed, and filter pad were installed; however, since the old cover hadn't previously leaked and didn't show any damage or distortions, it was reused. All bolts were tightened to spec torqs. The leak is along the side below the sentry, but it isn't leaking around its stem. 
 
Before installing a new cover and gasket I'm wondering if there is anything I'm missing here. Should a crankcase gasket seal also be applied to the surfaces even though the gasket had seal strips implanted?