leaking camshaft seals

What is your question?

I had valve cover gaskets and engine oil cooler replaced month and half ago because of smell coming from under the hood on the passenger side. Now there is another leak and supposedly the camshaft seals need to be replaced. Is this common? Should the leaking cam seals been replaced at the same time? What is the cost? I already paid $1054 for the valve cover gaskets and oil cooler. Can you Help!? Liz