The valve covers use o-rings. Likely it was pinched/nicked on installation, if installed correctly it should not leak. My vert cyl. intake was nicked when I took it off for a valve check but didn't leak. This kind of stuff isn't worth the hassle of the dealer. Check and replace if neccessary. Always grease the o-rings so they compress and slide smoothly into the bore in the head. Rotate the cover back and forth while pressing down square.
I wanted to ride the next day so I bought one at the dealer. I'm sure its a standard metric o-ring, measure it and you can buy a bag from a supplier for what one at the dealer costs. I do this for all the o-rings on my dirt bikes. I'll get these before the next valve check.