As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PHL FLT 954, EN ROUTE PHL TO DCA. DURING TAXI OUT, THE BRAKES WERE FOUND SPONGY, REQUIRING EXTRA PRESSURE TO BRING AIRCRAFT TO A STOP. THE FLIGHT RETURNED TO THE GATE WITHOUT FURTHER INCIDENT. MAINTENANCE BLED THE BRAKES. OK FOR SERVICE.