Camshaft cover oil leak

[TC89]

So I replaced the camshaft cover gasket less than a year ago because it was leaking oil and now it has started leaking again. I didn't use a torque wrench on the camshaft cover bolts but having checked them today I'm sure I've over tightened. They are only supposed to be done to 10Nm. Is it possible that over tightening has denatured the gasket? In which case I should just replace it again and tighten to the correct torque (didn't have an adapter to make my torque wrench take 1/4 " drive sockets last time)