In short, ignore my last reply, follow this one.
I've been given this as a recommended solution for you instead of what I have above. I've looked it over myself and can already see where it does better than what I was doing, so I'll recommend it myself as well. Put the contents of the gist in your functions.php file.
Put the following function call wherever you want them displayed:
It takes 3 parameters but none are required. If none provided, it'll fallback to defaults.
Author ID (default 0), Achievement Type (default all, if left empty), and limit (default 1)
No caching involved in this version as it's not having to do any laborious querying, so that's always a good thing. I did forget that once you have the ID, you can get most anything easily.