Mine do the same thing. It's minor and doesn't bother me any more. No other N/H/V, function is fine.
2008 M3 Coupe / DCT
// StopTech BBK 380/355 / Pagid RS29 / Motul / Apex Arc-8 / BFG R1 / Ground Control / MS filter / Performance spoiler / BPM tune // Road Atlanta 1:39.70 / VIR Full 2:10.87 / Barber 1:42.20