If you've been using one "MemoryCacheMethod" object in multiple instances of "Gw2WebApiClient" and are requesting authenticated endpoints with different access tokens, then you are likely to run into this bug. When using an instance of "MemoryCacheMethod" and using it with multiple instances of "Gw2WebApiClient", there's a possibility that cached authenticated responses are leaking to another request to the same endpoint, but with a different Guild Wars 2 access token. The latter request wouldn't start however, and would return the first cached response immediately. This means that the second response (or later responses) may contain the same data as the first response, therefore leaking data from another authenticated endpoint. The occurence of this is limited however. The Guild Wars 2 API doesn't use the "Expires" header on most (if not all) authenticated endpoints. This header is checked when caching responses. If this header isn't available, the response isn't cached at all. You should still update to at least version 0.3.1 in order to be certain that it won't happen.