[Ifeffit] S XANES question

A user on ALS 10.3.2 is taking S K-edge XANES and consistently finding a strong peak at 2484eV (calibration: gypsum white line = 2482.75eV). There's a shoulder at the nominal position of the sulfate peak. Now, peaks below sulfate I can understand, but since there's no such thing as heptavalent sulfur, what could give a peak *above* the sulfate white line? Anybody ever seen that? Yes, we checked calibration. mam