No, there's nothing you can do, and nothing you should do either. Just consider yourself lucky. There's no reason to feel bad if one of your questions gets more attention than you think it deserves. Obviously, for whatever reason, it has interested more people than you thought it would.
There are various reasons why it could have garnered so much attention (apart from its simply being a good question). First of all, you offered a bounty. Bounties increase a question's visibility by putting it on the Featured Questions list. In addition, bountied questions are tweeted by the SE tweetbot so a tweet about your question went out on the 2nd of July 2014.
Finally, and probably most importantly, your question's title contains "mount.cifs fails". This means that anybody searching for "mount.cifs fails", either on a search engine or on the site, is likely to come across your question. While the specifics of your issue are indeed pretty niche, as you say, mount.cifs errors are not, so many people have probably visited your question to see if it helps with their issue. That you only have 5 upvotes so far would suggest that most of them were drive-by visitors or that their issue was actually something different.
Anyway, don't worry about it, you've done nothing wrong and, with luck, the extra attention might eventually bring up the right answer.