So far fogged glass reports mention RC papers and no other paper types. Which also raises the question why one should use RC paper if the print will be framed. There are matte, satin and glossy RC paper qualities but I guess the last are mostly used and are not ideal for framing considering the reflectance.
Yes, that is what I've seen reports of as well. I did some more research into the topic over the weekend and the data that I have found confirms what I believe is going on. At the temperatures people are employing to dry prints, what is coming off is water vapor. If one looks at the vapor pressure data for glycerol/water mixtures, 99.96% of the vapor at 106 C is water so one is not seeing much if any glycerol coming off the print. The other unknown is what other organics Epson uses in the ink mixture (the 5-10% of the ink). Some have mentioned noticing an odor when they use the hair dryer method. Pure glycerol is odorless but the other organics could have an odor (many ketones used as solvents have a slight sweet smell). The observed fogging could be a result of these volatile organics that may still be present if the print is not adequately dried. The key thing is to get rid of the water so that there won't be any vaporization when the print is framed since this could carry trace amounts of either glycerol or something else to the gas phase and cause the fogging. Clearly one also needs to avoid extremes in temperature (including direct exposure to sunlight or other high intensity light source that can elevate the temperature) as this would alter the equilibrium causing gassing in a semi-sealed environment of a picture frame.
I guess the good experiment to conduct here is hinted at by Ernst and that would be to take prints on RC and Rag papers by the same manufacturer with a gloss like finish, frame them and see if there is discernible gassing. I can only report my own findings of long term display on Ilford Gold Fiber Silk that show no outgassing at all after 12 months of display at my office. 13x19 prints framed under plexi and mounted on a wall illuminated by normal office lighting are fine. I also have some prints on Museo Silver Rag and Portfolio Rag on the same wall. As I noted earlier, I took no special precautions regarding drying other than to put a sheet of archival paper over the print and prints were mounted on archival foam board with a 4 ply overmat after a minimum of two days drying time.