Script Execution Usage Limit Exceeded

Hi. I was wondering if anyone could help me out with this one:

I receive the following message after running a User Event script (after submit function):

Script Execution Usage Limit Exceeded
Date & Time: 8/3/2006 1:57 pm
Record Type: Invoice
Internal ID: 235
Execution Time: 0.48s
Script: CreateLessons
Script Usage: 100
Stack Trace:
#CreateLessons.nlapiCreateRecord(calendarevent)
#CreateLessons

My script contains a For loop that tries to create 5 events based on criteria from an invoice. I've been through the code and it seems to run fine but it consistently only creates 3 of the events before I receive the above error message.

It is clearly executing well below the 30 second governance limit but it seems that there is another limit coming into play that governs the number of records created.