That may have been how it appeared at the time, but it turns out that wasn't the case at all. It was later revealed that Christie sealed his fate with Trump in the 48 hours after the infamous "Access Hollywood" tape was released in October 2016.
Trump had called his senior campaign advisors to an emergency meeting at Trump Tower to chart their course over the coming days and salvage the campaign.
Christie was so convinced that Trump would lose the race that he wouldn't even answer his phone.
I'd almost be willing to bet $10,000 that these were the exact words out of Trump's mouth at that time:
"F#&% that fat bastard."
Bannon has said it was pressure from Kushner that got Christie booted.