A lot of the answers seem to be missing you point, as I assume that when you say
and this is my hash: abcd
You already are using a secure and accepted hashing algorithm, rather than you just doing pure obfuscation. In this case I would argue that some obfuscation of hashes that add security as often only databases get dumped without the code and in those cases - and only in those cases - an extra rule that is applied to the hash will make it a lot harder to figure out what is happening and which hashing algorithm has been used.
Of course it's best to make sure that the database doesn't get stolen in the first place, and it's likely that once an attacker has access to a database he will also gain access to your code, but making a hash unrecognizable would make at least quite a lot of those script-kiddie hackers give up.
All in all, would I advice you to do it? Nope, not really. Using a good hashing algorithm and salting your passwords should be more than enough, but in response to your question: yes it does make some sense, no matter how little.