This was at a show, but it wasn't "official", so it counts.
At the San Diego show (Canes), we were kinda wandering around, checked out the black metal beach BBQ (funny really), got a drink upstairs, and came back down. Well when you come down from the upstairs bar it goes right into the main hall where the stage is, which was open and no one cared. So we walk out the back door...right through an interview someone is doing with Mikael, and felt stupid. So we walk around a bit and then go back in the bar, Lacuna Coil was warming up so we stood around and watched that for a while. Peter walks in and starts chatting a bit later, and Mikael showed up right behind us with a bunch of old records (Doors, ect), guess he went shopping. Said hi, got damnation signed, and kept watching until they kicked everyone out for the show.