  Optical and X-ray observations of the quadruply imaged quasar 1RXS J1131-1231
show flux ratio anomalies among the images factors of ~2 in the optical and
\~3-9 in X-rays. Temporal variability of the quasar seems an unlikely
explanation for the discrepancies between the X-ray and optical flux ratio
anomalies. The negative parity of the most affected image and the decreasing
trend of the anomalies with wavelength suggest microlensing as a possible
explanation; this would imply that the source of optical radiation in RXS J1131
is ~10^4 R_g in size for a black hole mass of ~10^8 M_sun. We also present
evidence for different X-ray spectral hardness ratios among the four images.
