The Y2K Issue and Microsoft

While researching the thousands of documents for my book "Year 2000," I discovered some "1989" Microsoft file dates on client documents that I actually created and dated in 1999.   I did not transition from DOS to Microsoft Windows until the mid-1990's.  Around 2010, departing from Mil-Spec out of necessity, all of my office computers were given internet
access, which allowed availability of internet downloadable software updating. 

My question is - how can any Microsoft Windows Word documents be dated 1989, actually created in 1999, at a time when Microsoft had no remote access to my computers?

Microsoft has not been able to answer this question, nor any of my numerous resources. Can you?