External script and large intervals

Hi, 
I'm running hobbit snapshot from the 26th of august.

I'd like to run an external script on my hobbit server, but only once or
twice a day. 
So the hobbitlaunch.cfg should contain this : [my-script]
	NEEDS hobbitd
	CMD ~hobbit/server/ext/my-script
	INTERVAL 4h

I started to configure an interval of 60 minutes, but the status becomes
purple after 20 minutes. 
Is there a way I can tell hobbit to run the script with such interval
without a purple state after 20 minutes ? 
Thanks 
Nicolas Figaro