I think this has got to do something with one of the cache systems in eZp. Try this: If you clear all caches and load a page, you'll probably get the memeno warning(s) ; if you then reload the same page (without flushing the caches first this time), the warning message(s) disappear(s). Dont' worry too much about it. It is absolutely not an important/significant warning/error.
to Balazs: Yes, I know it do no harm at all, and it won't appear when using the cache. However I just want to find a way to solve this warning: the feeling is somewhat like Max's
As long as it is a warning, I wanna know how to avoid it and what's the meaning about it