I made two identical prints the day before yesterday, used a hair dryer on one (about 30 seconds for a 6"x9" print, which slightly curled the paper), then put them under plain paper for a day, then framed them in the clip frame. I will take it apart in two weeks and compare the two to see the difference, and report back.
Regarding matte papers, I've tested a number of papers for outgassing, and have seen no evidence of outgassing from any matte papers (by looking for fogging on glass in direct contact with the print). I'm not saying that no outgassing is going on, just that there appears to be no adverse effect from it. I have yet to find any glossy or semi-gloss papers that had none at all (this is before trying the hair dryer solution), but some have a pretty negligible amount, others a great deal.
Lisa