Valve cover gaskets are a common issue on any car with high miles. Even if they aren't leaking now, they could start leaking soon, and in order to replace them you'd have to pull the intake again! The valve cover gasket sets usually include spark plug tube seals as well. If those seals go bad, that could also cause trouble by fouling your plugs with oil.
So you are better off doing the gaskets now while the engine is still apart, so you only have to pull the intake once and won't have to do it again soon. I would also recommend ruthenium spark plugs, which last longer than even iridium.