Seibert made all five extra-point attempts and a lone field-goal try in Monday's 38-33 win over the Bengals.
Seibert's field goal was good from 42 yards out early in the fourth quarter, giving Washington a 31-20 lead. The Oklahoma product took over the kicking job in Week 2 and has since gone 8-for-8 on FGAs and 5-for-5 on PATs. He'll work to stay perfect in Week 4 against the Cardinals.