If I recall correctly, when my alk was very high as PH rose, alk tended to rise as well. It may very well have been from the process you stated occuring simultaneously, but when my ALK is below 200 it isn't as noticeable.

In any event, simply aerating has never lowered my alk. I had to reduce it with acid first, and try to hold it there as I aerated to bring PH back up.