Did they write something like "carry over carry back" on your BP? That's what they did on mine last night.

976 to DXB sat at the gate fully loaded for an hour due to a GPS issue then we pushed back, only to be told issue wasn't fixed, back to gate. I got off the plane, most stayed on, UA kept pushing the decision time back. I only had 8 hours in DXB before coming back, and a 5 hour connection on the return. Once UA delayed the flight 5 hours it became a trip in vain as I'd miss my return connection in IAD so they put me up in a hotel and noted my PNR.

So, am I entitled to the whole ticket amount, even though I flew the LAX-IAD portions (fly back today)?

Ironically, I'm very glad I rebooked early as 976 ended up canceling 6 or 7 hours after departure time. That ones going to hurt UA...there were something like 25 GS members on the flight and a huge list of 1Ks sitting in E+ that didn't clear an upgrade to J according to the agent I struck up a conversation with while I was being rebooked.