does no-store request invalidate?

Hello,

	Responses to HTTP requests with "Cache-control: no-store" are not
cachable. Recently, we came across a cache that does not cache responses
to no-store requests but also does not invalidate an older cached entity
with the same URL. When future requests stop using no-store, the old
cached entity is served.

For example, the following happens in our test case:

  1. Client requests an entity A without using no-store.
  2. Cache proxies the transaction and caches the response (entity A).

  3. Client requests the same entity A using "Cache-control: no-store".
  4. Cache proxies the transaction and does NOT cache the response.

  5. Client requests the same entity A again, without using no-store.
  6. Cache serves the "old" entity A cached in step #2 above.

Does the cache violate the intent of RFC 2616 in step #6? If yes, should
that intent be made explicit (I cannot find any explicit rules
prohibiting the above behavior)? 

If no, should the cache check that response in step #4 does not indicate
that cached entity A is stale? I cannot find explicit rules requiring
that, but we do have similar rules about 304 and HEAD responses
invalidating older cached entities.

Thank you,

Alex.