Do you get a "thumbs down" and not know why?

I've gotten a few "thumbs down" on my stories and because I'm old enough to know there will always be some people who don't like what I write, I don't mind that.  What is a little disturbing is that I've seen only one comment as to why the negative vote.  It would be nice to understand what I wrote that the reader didn't like so I don't make the same mistake again. 

It's enough for me that a reader read my story and voted with a thumbs up and no comment. Any comment, good or bad, is a bonus.  No comment with a negative vote seems a little a sniper attack.  You get shot at, but you don't know where it came from or why so there's nothing you can do to prevent the next shot.

Does this ever happen to you other writers, and how do you feel about it?.