UA 3908 then UA 331 at Houston
San Francisco → Houston → Washington National
Timetable, Houston time
17:58UA 3908 from San Francisco at the gate
16:55UA 331 to Washington National leaves the gate
22 h 57 apart on the timetable, overnight
UA 331 leaves 22 h 57 after UA 3908 arrives on the timetable: more than half a day, so not a connection we count.