If the rumor is true, clearly, but I can't imagine why Snow would muse publically about taking the job, and leave McClellan in limbo. That is not classy.
My guess is that McClellan has already tendered his resignation in order to work on his mother's campaign.
He hasn't commented at all for all we know, certainly not on here except to say he hasn't said anything on the record. Perhaps Gibson found out another way. Even if he did tell Gibson, that isn't a bad thing.
The bad thing is that it got out of FNC, and that is not Snow's fault.