Nah... they're fine, dont' worry about it.

My Sig LT-40 instructions say to use a 1/8 inch hole, and 4-40 bolts with lock nuts.
(I happened to used 6-32, and tapped the mount itself.)

1/8'th is about 1/32 larger than required for a 4-40 A 7/64 would be better. Maybe they figure that 1/8
gives people some room for error.

Here is great tool for centering holes in the future: http://www.greatplanes.com/accys/gpmr8130.html

good luck with it


edit, changed 3/32 to 7/64... 3/32 is the drill size if you're tapping a 4-40 hole... according to my tap set.