A question for affiliate marketers

I need some advice from Warriors who are experienced affiliate marketers. A website I have in a health niche made it to Google page 1 a few weeks ago for a highly competitive keyword. I put in a lot of work to bring targeted keywords up from page 23 to page 1, along with some to page 2 and 3, with credit to Warrior Forum info and WSOs.

I received an email from an affililiate manager asking me to tell which keyword I am having this success with. I don't want to be overly suspicious, but I remember seeing someone comment somewhere that affiliate managers can "steal" a good keyword from an affiliate marketer. I do not know what this means, but it doesn't sound good.

I wouldn't mind disclosing my strategies, but of course I also don't want to throw away months of late nights and early mornings creating and submitting articles, pages, learning RSS and the myriad other aspects of making a site work just because an Aff Mgr was fishing around and I did not know any better.

I am not doing any PPC, just pure organic traffic through adding a lot of original content and implementing SEO such as RSS, optimizing pages, and some topical backlinks. Can anyone offer some advice or insight about this? I appreciate your help.