Gordan wrote about this comparison on November 4, 2012:
The high altitude haze has become much more pronounced at the limb recently. While playing around with some mutual event datasets, I noticed two separate Titan-Dione mutuals were taken at almost exactly the same phase angle, but were separated by 20 months time. Whereas in early 2010 the high altitude haze was very visible only around the north pole, in late 2011 it was prominent across the limb. The Cassini team already reported drastic changes in haze layer altitudes. This actually makes it difficult to center two temporally distant snapshots on Titan "proper", but I registered it as best as I could. Phase angles were 61.6 deg and 61.0 in April 2010 and December 2011, respectively. Both were rescaled to 2x the pixel scale of the 2011 snapshot and rotated so north is roughly up.
Here are the original images used for the flicker comparison: