Disclaimer: the following is hearsay and rumor

What we over heard is that it had been "damaged on the ground in newark" and that it was a) delayed coming in and b) having operational difficulties completing the EWR to LHR route.

They weren't really clear or detailed on specifics. The official "letter" that was handed to us said:

"Due to operational reasons where there was aircraft damage due to weather, from a flight from EWR to LHR, there was an aircraft swap and unfortunately CO 19 will be delayed today."

We got a slightly different version of the story from everyone we talked to. Given that we didn't have any connection, my spidey senses told me to pull the rip cord and get on another flight. As such, we got out of there pretty quickly.