I'm interested in your point about the missing specular reflection(s) - From what I know the SR is the reflected image of the light source(s). It seems fair to say the component due to the sun would be very small compared to what you would see looking at the earth's oceans from orbit. As for the component due to Saturn the opposite would be true - Saturns reflected image would be immense (assuming Titan had a reflective liquid surface). Could it be that the SR's are either too small or too large to be easily discerned from the background diffuse lighting?

If I wasn't so lazy I would get the positions, sizes, reflectivity, luminosity(visible maybe, IR maybe not) of the three bodies in question and render it out in 3ds Max to get the predicted Titan SR from Cassini's flyby path.