Don't worry about it. I'm sorry too. We both misunderstood each other. It's not the first time it's happened, won't be the last. ;)
Another thing I do on short putts that are flat-ish is something else I remember from my class. We learned to pay attention to the drainage points on the green - where the water runs off. If I see that there is one directly behind the hole, for example, I'll try to hit it dead center. If I see that point 30* to the right of the hole, I'll aim inside left edge.
On the putts that are clearly on a 2% or higher slope, I'll do my midpoint read just like I would on longer putts. If I miss, it's, like Erik said, something I screwed up in my read or stroke (usually a speed thing for me).