Hey Chris,
first of all, thank you for the purchase!
I’ve double-checked the theme on a new WP instance, and could not replicate the “header already sent” error. From the message you’ve posted though, I can see that the WP Cache plugin might be the culprit. Could you please try disabling it and clearing the browser’s cache? If this does not remove the error, please try activating any other theme (e.g. the default Twenty Fourteen) and checking if the error persists. Please let me know of the results!
Sincerely,
Andrii / Satori Studio