This is possibly the busiest time for any one blockchain that happened ever... Imagine everybody sending all their coins to mintpal all at once!
It happens all the time. This is nothing special. I don't understand why everyone wants to send their coins to mintpal. What was wrong with Poloniex?
Because we saw the price higher there but unlike sending btc that poloniex accepts after 1 confirmation, about 10 minutes, it takes hours or a day to send Monero/XMR