Hash (# )in resource string returns /?%23

I'm finding that a # in a resource string is being converted to /?%23 when being retrieved on my F5, but as # in the Sim. 

Am I breaking a convention by including a # in a string?

How to get it to return the # ?

[UPDATE]

The problem has disappeared as mysteriously as it appeared, so I guess since I am unable to replicate the problem, I'll have to withdraw the comments . Interesting.