Cook missed Thursday's practice due to a personal matter, Chris Brown of the Bills' official site reports.
Per Alaina Getzenberg of ESPN.com, Cook missed the practice in anticipation of the birth of his child. The Bills will release their final Week 3 injury report following practice Friday, when it'll be known whether Cook rejoined the team. In the team's Week 2 win over the Raiders, Cook carried 17 times for 123 yards and caught four passes for 36 yards.