Generally the alt coins take a hit when BTC rockets up so fast....I think it's a flocking mechanism with the buyer. Once BTC starts to settle....the alt coins go phasic with it, and I think that's when people start to pull profits or any type of funds from BTC and start spreading it around the market. Could be due to fear of volatility, rumors or whatever else. The price didn't just go up last night, the volume was growing as well, and as the volume declines, those buyers start to spread around the cryptosphere.