The price of BTC has gone up, if the spread between the alt currencies and BTC remains the same it means the value of the alts is increasing. For the coins to keep their same value, the spread has to go down.
If you want more details, I wrote about it on my blog:
http://de-crypter.blogspot.com/What he said. LTC for example hasn't gone down, the price of BTC has just gone up, that's all. Little FYI, last time BTC shot up fast and stabilized over $1000 a few days later the alts caught on fire and moved up faster.