I go to UChicago (for undergrad), and I've been admitted to top 5 biostats programs with B range grades in (accelerated) real analysis (all A's or A-'s but one in my remaining math/stat classes though). I would just take it for a quality grade and wouldn't worry about it too much if I were you. Many adcoms would assume that a P means that you were on the verge of getting a C range grade in the class.