Hey Xx DBENC xX, welcome to the User Group Forums. Actually, it's a trademark, not a patent. One of the big differences between the two is a trademark never expires.
DiMarzio's lawyer got a trademark on the Lipstick Tube Pickup for one of his other clients, WD Music. He used the same theory that DiMarzio used to get the trademark on double cream back in the '80s: acquired distinctiveness achieved through five years of continuous and exclusive use in commerce. As if WD was the only company selling Lipstick Tube pickups from 1995 to 1995 (sorry Danelectro, Charvel, Ibanez, Jerry Jones, Chandler and Seymour Duncan, I guess you don't exist).