I just realized something. Sam’s S6 arc is similiar to Buffy’s in Season Six of her show. At the end of both of their fifth seasons, Sam and Buffy went somewhere (Buffy through death, Sam through a hole in Hell) only to come back later on changed. They both became emotionally distant and in some ways, numb because of the experiences they underwent prior to their return. I think over the course of the season, Sam will regain his former self through a series of events like Buffy did eventually. So we may have put up with cold Sam for a while.