So the email was planned to go out in advance.
Now, that's not inherently a sign of an op - just asking for comment, a common and good journalistic practice, can warn people that the shitbarometer is dropping.
How do I know it was a plant?
Warren had an answer ready tonight.
That was not off-the-cuff Warren. That was debate-prepped Warren, and the difference shows.
Warren knows a shot is coming in advance from Politico against Sanders.
Politico either manufactures its source or comically fails to vet said source was actually deployed by the campaign.
The result feeds dead into Warren's soundbytes of the week.
It's an op.
Choose wisely.