Engine revs when shifting a 6-speed

I just bought a Tacoma, 4X4, V6, 6-speed. I like this truck a lot (so does my wife!) but, when shifting, the engine speed does not fall off like I'm used to. In some cases, like when shifting from 4th to 5th in acceleration, the engine increases as much as 500 rpm before dropping. Most often is simply takes way too long for the engine speed to decrease during a gear shift. Dealer says it's normal and I can't believe that. This happens whether the engine is hot or cold. What gives?