To clarify, the IPN we received from PayPal was not an actual payment notification, but rather just a notification that the buyer started a subscription/recurring payment plan. Our system didn't know what to do with that and did not see any actual, nonzero payment made yet, so it simply forwarded a copy of the IPN data to you. This would also be the case with other administrative IPNs notifying of payment plan cancellation, modification, etc. unrelated to an actual payment being made.
If there had been an immediate payment made as well, we would have received a separate IPN for that, which our system should process as a regular paid transaction. Since you'd set things up with a 1-week free trial, no actual payment was made yet, so our system would not receive IPN regarding payment until that week had elapsed. This means at present, our system cannot (even unofficially) process free trial periods for subscription/recurring payment orders before the first actual payment is sent.