How to get info out of a fetched JsonDoc

Question

The following returns a JsonDoc:

String fetchedJSONObject = jsonDocList[i].GetJsonDoc();

In my case 'fetchedJSONObject' holds the following string:

"username":"TOTtester", "expirationdate":"08/30/2014"

 

I know that I could do this with normal string library functions but Is there a App43/JSON way to pull the date out of that string?