No surprise, it seems normal. The M3 has quite a bit of power, and BMW doesn't want the average driver to get over his/her own head. Since it also senses has gas pedal position, it determines when/if letting the reigns go would be appropriate. I assuming since you lost a bit of traction, it thought you were in a low traction situation.......at the same time you left your foot planted. Even if the tires hooked up momentarily, it probably decided that letting it immediately back to full throttle would have caused yet another loss of traction. Basically, you might know it's perfectly dry and okay.......but DSC might not and wants to keep you safe.

If your previous X5 was a xDrive equipped one, you probably aren't used to DSC coming on. On the xDrive models, I notice that DSC intervenes much later and much less than in rear-drive models.