The first thing I would do is check to see if you can find those items on the content search side. Do a regular search for content with that same name. That author mini-search by contact feature uses the search system as well which should mean that search is not configured properly. When properly configured all search results are security trimmed, including that mini-search within the profile information. If security trimming is not taking place, then you want to verify that the content access account IS NOT an administrator account but just a regular domain account.
Here are the instructions for changing the Default Content Access Account: http://technet.microsoft.com/en-us/library/cc261796.aspx
If you have to change this account, which I suspect you do, then you will want to reset the index and initiate a full crawl afterwards to rebuild the index with the correct Access Control List (ACL) information so that security trimming will work.