They were almost certainly in touch before, but the deal being done in 5 days means that the sony announcement could have been the event that pressed the oculus team at look at an acquisition more seriously.
I think it's the other way around. Because of Sony's involvment, I'd say investors from probably many large companies were pressed to buy stake in Occulus Rift ASAP to make a dent in the VR market should it become big. Facebook probably had the biggest offer on the table and that's the end of the story.