Stop amazon ec2 health checker from checking a file

Question

I have a php file in my amazon webserver which runs a bulk email script which sends around 50 emails to the employees in my company, i have set up a cron task to run the .php file every monday morning but it seems that this file gets triggered automatically, looking at the access logs im pretty sure its due to amazons health checker, is there a way to force it to ignore my file? or if there is a php method that can do something. Thanks