I'm not sure why I'm getting spam. I deleted the address last night, and it showed up again this morning. I chatted with MailChimp today and they were puzzled as well. Funny thing is, I cannot "report" the email as spam to MailChimp because they don't have that feature. I Googled the email address, and it's definitely on a few spam lists. Customer support said the only way to handle this is to create a static segment that holds this address (let's hope it's the only one), and never send to that segment.
Oh well. Thanks for the response.