The IRS accepted my explanation and revoked my penalty – now what?

Back in January, I was assessed a penalty. I submitted an explanation for it right away. Around April I paid the penalty plus interest just to be safe.

I just got a letter telling me they have accepted my explanation and rescinded the penalty. Yaay. But the letter did not include a check. Should I expect a refund of the penalty plus interest separately or do I need to do something to get it refunded?