That has actually puzzled me quite a bit....
It seems as if when submitting an edit, it checks to see if your most recent post was within a minute....
The interesting part is that actually submitting the edit does not 'count' as a post... So you can edit your edit seconds after...
I think the solution would be, to just make it so edits don't check that most recent post time... That way we could still have a bit of safety from potential spammers, without making editing frustrating.
I'm not sure how complicated that is though, as it's up to TYP...
Also, why did you just throw that request in this thread? =P