Mines the same on the passenger side, but ive found that the prev. Owner had worj done and the valve covers were bent at the bolt holes because the bolts have a centering grommet on it that if you tighten down it will bend a point into it. Plus the gasket was messed up with the sharp edges digging in. I had mine off and flattened the cover surface using a vise and a socket to make them smooth ( a week ago). Ive found its best (depending on condition of gasket, if you set the gasket on the cover and pop your bolts through it will hold it in good enough to carefully put on the head. Or just do a 1 turn in so its loose on all bolts then pull up on cover as you hand tighten the bolts. Also the bottom back bolts on pass side are impossible to torque so its really just guessing with a wrench.
Check the bolts on the valve covers, if theyre grimey then its valve cover gaskets most likely