Taking It Back: R.E.M. guitarist Peter Buck, arrested at London's Heathrow Airport on Saturday and charged with assaulting crew members in an alleged drunken rage during a flight from Seattle, apologized on Monday. "I am very sorry for the incident and, of course, very embarrassed about the whole thing," Buck, 44, said in a statement. Buck was arraigned Monday and posted about $43,000 in bail; he is to return to court June 18. In his statement, Buck also said he is grateful to the London court for allowing him to proceed with plans for an upcoming R.E.M. concert tour in support of the group's album, "Reveal," which is due in stores next month. Though Buck was advised by his attorney not to comment further, R.E.M.'s London-based agent, Bob Gold, called the guitarist's alleged outburst "completely out of character."