"Jack
According to the records in the database John made the offer first at 16:01:07. This was followed by Tony's offer at 17:11:49. So in the end it seems like John should have gotten the driver anyway.
This is almost certainly related to the "fix" I put live a few days ago to prevent drivers from being locked in to an expired bid. It seems to be a bit too trigger happy, and put a driver back on the market that was already taken. I'll work on improving it further.
Edit: I've applied an update that will stop this from happening again.
You may also want to look into the variable that Robinson was my driver before and I was resigning her - the acceptance e-mail I got had a "Re: Driver Contract" subject line and what might have happened was that the system essentially duplicated her original acceptance message.
I was finally able to clear her off my shortlist by clicking "Reject" in the e-mail, by the way.
I should mention that when I sent the offer there was no sign of any other competing offers either.