Passwords needing to be reentered after full scan

Just curious as to what's happening, but I have NS set to do a full system scan every Sunday morning at 7am. After the scan, I notice all the sites where I had entered a password that are remembered when I revisit the site during the week, need to be reentered after the scan. Examples are: this site, Yahoo mail, other forums, etc. This does not involve sites that require a password every time you log in (banking sites and others like that) but only the ones that ask you if you want to "be remembered" on this computer. I'm sure this is related to the fact that after the scan, I usually see "total security risks detected.... 1" and "total security risks resolved... 1" and it shows the "1" to be "tracking cookies".

 But something different is happening during a full scan because if I ask it to run a quick scan, I see it also detects tracking cookies, but deleting them doesn't cause the passwords to be lost. Just wondering why a full scan considers those password "cookies" something that needs to be removed??  It's probably not a bad idea to reenter them each week (my vault fills them in quickly) but why does NS consider them to be a "security risk"??? Thanks for any explanation.