if seafoam ate the gaskets everyone who ever used it would have this issue. It might have eaten gunk away that was plugging an already leaking valve cover. If it is leaking from between the valve cover and the engine I would think the most you would need was replacing the gaskets which apparently already needed replacement. Or if a valve cover job was done and the gaskets were not seated correctly. (need more history)

I believe you just purchased your VX. It is not unknown for an unscrupulous seller to plug leaks in an order to deceive a buyer. (not saying that is what happened) Either way not a big fix if just the gaskets need done.