NB. For Heston, this is someone revalidating their Micro NPPL rating just a week after issue, no waiting until the second 12 month period - although, technically, you have "waited" since the second 12 month period is calculated from the SSEA date!
Oh OK I see what you mean now. Its sometimes helpful with these things to consider the extreme examples as a test of the logic. Well, every day is a school day.
(In your example it would of course still be necessary for the required number of hours to have been flown in both the first and second 12 month periods calculated backwards from the date at which the micro rating is to be revalidated (and as you say, as long as one hour was micro, the others could be SSEA))
And thanks Beagle - I wasn't aware of that AIC, though I should have been!