Question About Stop Loss

I’ve had several trades close saying it hit the stop loss when it hasn’t even been close. Why is this? The two horizontal lines are the stop loss and take profit points set as you can see in the trade log. The vertical line is when the trade was entered. This is just a demo account.

Here is an example:
http://img685.imageshack.us/img685/2536/mt4t.jpg

I think that MetaTrader plots the chart according to the bid price and the ask at that time was higher than what is shown by the candle nearest to your stop (assuming you went short).