No. You are not required to send payment coupons, or late payment notices. However, if you do this for all other COBRA participants, then you must do the same for this PQB. The Initial COBRA notices received as a new hire explains this as well as your COBRA notification/election packet should state this.
Per the DOL: The plan is not obligated to send monthly premium notices, but is required to provide a notice of early termination if continuation coverage is terminated early due to failure to make a timely payment.