NEW : NFL . was `` nervous and not thinking , '' a source says . NFL says its system was late to obscure the gesture . The Rapper M.I.A says the gesture was inappropriate and disappointing . M.I.A . The halftime show generated 8,000 tweets per second .
NEW : NFL . was `` nervous and not thinking , '' a source says . NFL says its system was late to obscure the gesture . The Rapper M.I.A says the gesture was inappropriate and disappointing . The halftime show generated 8,000 tweets per second .