Has Titan’s atmosphere expanded? Check out
this article?

"Images showed that the diameter of Titan's X-ray shadow was larger than the diameter of the moon's solid surface. Why the difference? The answer: Titan's atmosphere. The difference in diameters reveals that the X-ray absorbing region of the moon's atmosphere reaches from the surface to a height of about 550 miles."

"The upper atmosphere's extent is consistent with Voyager 1's 1980 measurements, or 10-15 percent larger. But according to Hiroshi Tsunemi of Japan's Osaka University, Saturn was closer to the sun in 2003, so possibly prompting Titan's atmosphere to expand slightly from increased solar heating."