No explanation as to why and the one docent I asked did not even know there was a sign. I did not run across a keeper to ask, but I am hoping this might mean a pregnancy? (Pure speculation on my part).
@Timmiegun I think so. The birth was revealed on a news release posted by Cincinnati Zoo, whose scientists assisted with the artificial insemination. (It was also revealed to me in a personal conversation with volunteers). However the Desert Museum themselves never made an official announcement because for some reason they are deciding to keep mother and baby off exhibit until baby is shipped to another zoo.