Even John Legend calls in sick. The 37-year-old R&B musician tweeted that he would have to postpone his concerts in Columbia, Maryland, and Camden, New Jersey, on Tuesday and Thursday. "To all my fans in DC/Maryland/Virginia and Philadelphia/South Jersey, I want to personally apologize," Legend wrote. "I've gotten sick and need a few days to recover and rest my voice." The "All of You" singer assured fans that new concert dates will be announced "very soon," and seating will be honored.