I think there is an important lesson here for all of us....it's difficult, almost to the point of impossible, the objectively evaluate your own beer. Confirmation bias is powerful, and we also all have our own blind spots in tasting.
As per usual, Denny is right on.
In my much less educated opinion, the beer at the top of the glass will taste the same as the beer at the bottom. If it tastes weird, stop drinking.
Once upon a time I sipped my very first wee heavy and convinced myself that it was supposed to taste like old caramel flavored popcorn. Thinking I was so sophisticated for being able to discern such complex flavors I kept drinking. As a result I never got any taller from that point forward.
Probably had nothing to do with the beer and everything with the fact that I was 35 at the time, still that was massively diacetyl-ly.