I have a couple in mind:
Madrid with a 28-13 win over 1A semifinalist Van Meter
South Winn with a 34-12 win over 2A runner-up Waukon
Emmetsburg routing 3A Storm Lake 42-7
Those first two probably aren't big surprises that those teams won, especially South Winn over Waukon as they lost quite a bit of talent from last year, but the margin is what impresses me the most.
With E'burg, I know Storm Lake has not been very good (just 2-7 last year), but it was nice to see them get back to form with a wide victory margin after all the seniors they lost from last year's squad that went 5-4.