If this is the case, perhaps another callback could be added, of what name I do not know. The confusion for me here was that it was 'post::store()' -- 'post-commit::store()' I think is another one, which I possibly wouldn't presume it to be true for... but I feel 'post::store()' should be almost equivalent to running something right after the ->store() call. Obviously the benefit of a hook callback is that if you store the record in multiple places you can just add the callback rather than repeating whatever the code is after that needs to be done.
I don't know if there is a clean way to "fix" it without breaking backwards compatibility, but at the very least I feel it should be clearly documented somewhere that the exists() method will return FALSE during all ORMCallbacks and does not return true until store() returns. The code which raised this issue is fixed otherwise, so it's not some huge deal... it was just sorta confusing and/or non-intuitive.
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