Nope... they are actually just right. While cleaning up after brewing I have been paying close attention to the slots to see if they get packed with grain. On average, I will have about 10-15 little pieces of crushed grain lodged in a slot or hole. That is nothing that is going to effect flow or efficiency.
Just take your time with the cutting wheel on the angle grinder and you will be good. Don't force the blade... let it do the work it was designed to do. My only screw up on this FB is seen in this photo at about 7-O'clock mid way down the group of slots. The grinder got away from me and gouged a little bit.
Try to calculate your open space percentage and keep it above 15%. I think I have 17% open space in this one.