Just happened to notice this oddity on a flight I booked yesterday. I didn't notice then because the departure and arrival times are normal. However, the flight length displayed on UA.com is not normal:

ORD-SEA = 3 hours 36 min
Departure 12:00 pm, Arrival 2:36 pm

Over two time zones, that's a 4:36 flight.


SEA-ORD = 5 hours 2 min (should be shorter eastbound!)
Departure 2:05 pm, Arrival 8:07 pm

That's actually a 4:02 flight.

Not that any of it really matters, but I wondered if others are seeing this, indicating a time zone issue in the system, or if its just my one weird flight?