Stop buy order triggering issue

I recently saw an issue in an EA during testing on a 1H chart.  The EA issues a stop buy order at a 1.53824 on GBPUSD.  The high never reaches this level before it back down according to the history center.  However, the stop buy order was triggered and filled.  Any reason why the order is triggered?  I would not expect the stop buy order to be triggered until the high reaches 1.53824.