first of all, he needs to shut up and leave it in the past
second of all, yeah right single use stays in system for a month. subsequent tests would have reflected low levels getting lower *BUT i don't know if the nfl operates like the court system/probation, where if you test positive, you may continue to test positive while showing lower levels on each test until the test shows it's out of your system - over the course of a realistic timeline.
Fred Davis suggests single use led to multiple failed drug tests | ProFootballTalk