Should I be worried about a small drop in senior year grades

I got accepted ED1. First semester senior year I got straight As which was an improvement over a lot of bs frosh-soph year. this semester (at worst) I might get 1-2 bs and 1 c (probably in math) the other 3 classes are sure “A’s.” Is there any way this could cause me to be “reviewed” or am I well within the boundaries of “acceptable decline”?

No you shouldn’t worry at all. Senioritis is extremely common for kids that get acceptances. As long as you don’t drop below a C, you should be fine.