Module Integration - Inserting system message into a panels node view

I am working to modifying the signup_pay module to work with my panels implementation. The application I am working on displays CCK content types called events. The events are signup enabled and all works ok there. Some of these events need to be paid events. We have signup_pay working ok and it modifies the signup_form that signup provides (well it is a patch, but it works.)

What I am trying to accomplish is as follows: signup_pay uses the nodeapi function to insert a drupal_set_message into nodes when the user has signed up for an event, but payment has not been received. It is just a short message with a link to the payment page. The trouble is that the module inserts the message when the nodeapi $op == 'view', but with the node being viewed as panels pages, the nodeapi view op doesn't happen and the message doesn't get presented.

My thought has been to create a small ctools plugin for signup_pay that will call a function in signup_pay with the message. Is this something that can (or should be done) with a content type plugin? or is there a better way? Thanks.