Good info, not having fished them much and recently having an opportunity to do so I noticed the same thing. Big salmon flies on the water weren't getting looks at all and trout were nailing the top of the water (or so I was thinking). After getting a good skunking on big ugly flies I let myself realize there were caddis coming off as well.
When I really set back and looked at what was going on I allowed myself to get salmon flies out of my head and see fish taking emergers below the surface. I was so excited about big top water action that I missed out on a lot of catching. I did however learn a good lesson, and that's part of what all this is about. Later on I confirmed this with a local guide and he says he believes after gorging themselves on a big hatch most fish will settle into one location and become a little picky on what they eat. I guess I'll have to continue investigating this when next year comes around.