In an attempt to help subscribers track whether or not a trigger has fired, we’ve created a Trigger Log report which will show a running log of all triggers that have fired. We’ve not been collecting that data previously so the report will only show a log of triggers that have fired after October 23, 2013.
The report can be accessed at reports > triggers log report
Keep in mind there is a queue for all Triggers, that queue is flushed every five minutes. So it could take up to five minutes for the trigger to fire.