I’m not sure this is so routine. En Banc hearings are so rarely granted Circuit Courts of Appeal typically forbid any party from filing a response to such a request unless the Court orders or invites one. In the case of this Court, see Rule 35(e) of the Local Rules. This is prevent the unnecessary expense of a party responding to something the Court is going to dispose of itself. The fact that a response has been asked for, suggests that the en banc petition has gotten some traction.
“...The fact that a response has been asked for, suggests that the en banc petition has gotten some traction.”
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It likely suggests that one or more of the Appeals Court judges asked for a vote on the en band petition. If, when polled, none had asked for a vote they would have simply automatically sent it back denied.