I did the exact same thing! I went back and put a cleco in every hole but the center (countersunk) ones and then squeezed them together with my fingers just to make sure something else wasn't going on. And, yep! ..... they were under-countersunk. So, I got out the cage and slowly proceeded, rechecking (same as above) until they sat flush. Then, I wiped the area down with a little acetone, and lightly re-primed the area. I use SEM self-etching primer from a rattle can, so it was very easy.
Incidentally, I also butchered the first set of front spar doublers, front spar halves and horizontal stab tip ribs and had to order new. I think I've made every mistake possible so far. And, I think I hold the record for the longest elapsed time build for an RV-8. So, ..... don't sweat it man!
