There are several mechanisms in place to prevent, detect and act on hostile downvoting. Think about someone downvoting all your posts because of a dispute, or 'tactical downvoting': when someone downvotes the other answers of a question he has answered, so that his post is better visible.
Downvoting is a privilege that is awarded to users at 125 reputation, because they are considered to know the SE format and this site well enough to use it wisely. It is not defined what exactly deserves a downvote (that would be impossible), but there are guidelines.
From the help center:
Voting down, also known as "casting downvotes", is how the community indicates which questions and answers are least useful.
Use your downvotes whenever you encounter an egregiously sloppy, no-effort-expended post, or an answer that is clearly and perhaps dangerously incorrect.
I have had a look at your reputation history and it seems you have had 3-4 downvotes over the past couple of weeks. That is a very normal, perhaps even relatively low number of downvotes for a user who is as active as you are. Indeed, it is common to receive a downvote now and then, and they cannot always be explained. So I wouldn't worry about them - until one particular post starts to attract many downvotes, perhaps.
Since downvotes are anonymous and nobody is required to explain them (which is a good thing), it is impossible to answer your question if there is this issue. Unless you have a clear idea that some kind of questions (about some topic / in some writing style / etc.) attracts more questions than others, it isn't very meaningful to discuss it, I think.