Lou Ekus recommends dosing for Calcium not Alk.I do not believe that such a rise could be caused by AFR. It must be for other reasons, or is test error (most likely).
Do you recall how much you added each day? That rise would require a large dose offsetting a very large demand for alkalinity (10.5 dKH) that came from something other than calcification. Unless you are dosing mineral acids tot eh tank, I don't see how that can happen.