Lisa, I think it is the clip-frame without a mat that is causing the problem.
Artwork on any paper regardless of techniques and color applied needs a mat if framed behind glass to prevent condensed moisture to build up and fog the glass - warp the paper and so on. Paper needs room to expand and contract due to changes in the humidity. Traditional C- Prints would even stick to the glass if mounted without a mat and exposed to moderate humidity, causing permanent damage to the print. Even a high grade watercolor on cotton paper acts up, if it is left without space in a clip-frame (ugly mottled specs, pigments on the glass and warping). Matting is not a cosmetic idea, it has a purpose.
Anyway, I use the Epson 2100 for many years, the 2400 since the beginning of 2006 and many different papers. 'Outgassing' has never been an issue at all. I let the prints dry for about 24 hours or less - just standing them up in not too clean air, frame them with a mat, put them in archival sleeves (which are open on one side - to let air in) for display in a portfolio or store them in drawers without protective sheets in between.
A different technique for display without a mat would be DiaSec. In this case, the print is covered face up with a silicon-type glue and permanently bonded with a sheet of acrylic. Looks very nice, because it adds depth and luminosity to the print. Amazing. If you ever see that in a gallery, you want it. There has been some question recently, whether or not there is a slight yellowing over time due to the glue. One should hope not, because a lot of the highly prized artists today have their prints displayed (and sold) that way. The down side is that it is expensive and can only be done by professionals, as yet, as far as I know :-))