I just ran through 20 or so Word imports and never saw that. What I did find, though, were quite a few instances where the a word author used the manual styling and numbered list button to make a text line look like a heading1. Some others used headings in a couple spots, then did the whole fricking thing as a numbered list, so all the headings were <OL><LI><P> and to top it off, they applied manual formatting to the number too.
I'll bet you a cup of coffee that your doc is similar. If M$ had implemented a number system in Word that actually works properly all the time, we wouldn't be in this mess
