I burned my "eyes"

Burdseye maple that is.  After resawing a piece, I rune it though my Grizzley thiskness sander, belt speed about 40% with 220 grit paper to remove the bandsaw chatter.  Unfortunately the friction from the sander turned the eyes brown.  Should I run it through faster, use a lower grit, or sand by hand?   An orbital sander with 220 grit helped somewhat (board on right compared with left).