My report says my 3 of my 'most contacted' emails are gmail accounts I've never heard of. Googling these email addresses returns lists of known spammers. However clicking on the emails in the report itself shows no known results in my gmail. Has anyone else seen this? Should I be concerned? What should I check for?

I already re-checked that I have no forwarding addresses set; the addresses do not show up as autocomplete if I begin to type a message to one.

Could it just be a bug? The numbers are "14 emails sent", so not a huge amount, but I'm slightly disturbed by this and can't find any other clues yet.