Mt.Gox has been an unreliable source for the exchange rate for quite awhile now. Bitstamp is pretty much the current gold standard for USD<->BTC rates (Coinbase

Mt.Gox has been an unreliable source for the exchange rate for quite awhile now. Bitstamp is pretty much the current gold standard for USD<->BTC rates (Coinbase and BitPay are based on the Bitstamp rate).