This happened when I was playing No Good Gofers. When Buzz told Bud to keep that ball under wraps, he means it!
Nope, what happened was I started mist multiball and just grazed the mist ball. My ball then sticks to the mist ball and "tags along" with it until the mist ball is parked. It either disconnects when the magnet is turned off or hangs on due to residual magnetism. By that point the game either gives me the multiball or it goes through a ball search.