Investors are starting to warm up to the non-agency mortgage market again — or, at least, AIG (AIG) sees value here. Bloomberg is reporting that the beheamoth insurer has been buying up residential and commercial securities at a fast clip since late 2010. Our favorite quote in the story is from Bernstein & Co‘s Josh Stirling, who calls the non-agency market “massively  illiquid” and “under-loved.”