Hi,

I use Windows Defender a lot, and have had no problems thus far

I test individual files/folders against Jotti and virustotal:

https://www.virustotal.com/

Basically they test a file/folder using most of the latest AV proggies and definitions. That means that you can expect no more than a 40% hit rate, if that.

I would not worry about what you are seeing myself, until I had run an online scan, and gotten positives.