The `Twilight` heartthrob - who showed off his newly-shorn locks earlier this week - is concerned some of his tresses may end up being sold at auction after they vanished from the hairdresser`s floor. A source is quoted by gossip website Absolute Now as saying: "Robert has had his hair cut short for a movie role but his discarded hair has gone missing. "Someone collected it and Rob is concerned it will end up in some tacky auction. It`s probably about the most valuable hair in showbiz!" When quizzed as to why he cut off his famous blond hair, Robert - who is dating his `Twilight` co-star Kristen Stewart - claimed it was due to an infestation of head lice. He joked: "I got a terrible infestation of nits and I had to shave it off." The `Remember Me` star showed off his new look during a romantic break with Kristen to mark his 24th birthday last week. The `Twilight` actor - who turned 24 on May 13 - spent last weekend at the Ritz-Carlton in Laguna Beach where they dined at the Raya restaurant before taking a midnight stroll on the beach. A source said: "They were making small talk, not chatting a lot, but seemed very comfortable with one another. They were low-key and not bugged by other guests, left to their own devices."