I wonder about that. In 2001 2 Republicans, Lynn Wheeler (incumbent) and Pat Mumford (first election), were the highest vote-getters for the at-large seats. Democrats came in 3rd and 4th and then more Republicans. Lassiter is almost an incumbent from his years on the school board; he got the most votes of any at-large school board candidate in 2001, ahead of 2 Democrats, in a non-partisan race.
What changing demographics are you referring to? I haven't seen numbers; the only thing I've really heard about is influx of Hispanics and Yankees.