Dr. Sidney Kramer, chief of cardiac surgery at Lenox Hill Hospital, is having 'one of those days,' he confided to a colleague Monday. 'I don't know if I woke up on the wrong side of the bed this morning or what, but I've been Mr. Butterfingers today,' Kramer, 51, told anesthesiologist Allan Chang following 'the heart transplant from hell.' 'Somebody shoulda locked up those scalpels and hid the key from me. Yikes. Oh, well, guess there's always tomorrow.' 