Urgent: PayPal IPN Warning from Events+

I received an email from PayPal this afternoon threatening to disable IPNs for my account. They sent this URL as an example problem: http://www.mydomain.org/wp-admin/admin-ajax.php?action=eab_paypal_ipnhttp%3A%2F%2Fwww.mydomain.org%2Fwp-admin%2Fadmin-ajax.php%3Faction%3Deab_paypal_ipn&blog_id=1&booking_id=224http%3A%2F%2Fwww.mydomain.org%2Fwp-admin%2Fadmin-ajax.php%3Faction%3Deab_paypal_ipn&blog_id=1&booking_id=230http%3A%2F%2Fwww.mydomain.org%2Fwp-admin%2Fadmin-ajax.php%3Faction%3Deab_paypal_ipn&blog_id=1&booking_id=236http%3A%2F%2Fwww.mydomain.org%2Fwp-admin%2Fadmin-ajax.php%3Faction%3Deab_paypal_ipn&blog_id=1&booking_id=237

What's weird as that those are all legitimate purchases from different customers. Any idea how this could happen?

Thanks!