Well it was the complimentary colors you mentioned; green seen in the grey and magenta measured in the grey that made me think it could be bronzing. The spectrometer reading shifted by the bronzing, the profile compensating for the magenta reading and delivering a green bias in the printed grey. Quite like I observed once.
Fluorescence usually shifts shorter wavelength energy to lower wavelength energy, how that would work out on the ink hues you mentioned I do not know but I think the cyan is then the most likely candidate for fluorescence and not the yellow. There is some literature on the web about dyes masking paper OBA effects and fluorescence in dyes themselves.
Met vriendelijke groet, Ernsthttp://www.pigment-print.com/spectralplots/spectrumviz_1.htm
January 2014, 600+ inkjet media white spectral plots.