Technically and for audit purposes, if the patient signs the check over to you it's a patient payment. It would be no different than if the patient put the check into their acct and then wrote you a check. Also, IF this is a group health plan goverened under ERISA, the claim was the patient's and the reimbursement was the patient's making the payment to you from them in any form a patient payment.
Many BCBS plan's don't have to honor assignment of benefits so we always collect at the time of service for my clients that don't par with BCBS to avoid that.