[nesslar]

First of all, the valve covers should not be warped, right? I think it's pretty obvious that the gaskets are bad/cheapos, covers improperly torqued, or both. I can't believe that kind of leak after putting them back in place. I could probably do a better job myself. I think they owe you one.
As for sitting, my Carrera will (usually) leak a drop or two after it sits for several days, then when I drive it for days in a row, the little leak goes away usually, sometimes a drop now and then, on the right side. Recently I had a nice stretch (weeks) with nada leaking. Your leak on the cardboard is matched fairly closely in size by mine, on cardboard also, but it took me a couple of years + to get there.