I thought models doing Pay Per View either asked photographers to do a free shoot specifying they wanted pay per view content or paid the photographer?
Kudos to the model for being honest and specifying he/she was going to use them in Pay Per View after being paid for their time, because otherwise you just wouldn't know unless you subscribed to the channel I guess.
It's up to you but if you feel generous you could renegotiate your payment to the model and even a payment to benefit you if the model liked your pics so much. Though I would read the Pay Per Channel terms and conditions, by allowing the model to use your work on there, it may restrict use of that image elsewhere which could include the copyright holder use, just in case you wanted to use it.