I interviewed at Umass and they have a Medical ASL elective. maybe they have similar classes at other schools? you could have a chance to learn that later if you pass it up now. On the other hand, I think the general consensus is that admissions departments don't care if you have a minor or not. do which one you find more appealing. I vote ASL, it's interesting and would only make you stand out from the cookie cutter applicants if anything