Google Blocked My IP Address

I recently wrote a script that grabs a list of popular artists and then runs a total of 40 Google searches.

I ran the script a few times (debugging) and then Google blocked my IP address! I now get a 503: Service Unavailable every time the script runs.

Does anyone know how I can tell Google that I am a human and I am just running a few hundred searches?

Or, is there a way for me to use the xgoogle library to query Google without getting flagged?

Or, is there a description of how Google handles requests from a certain IP address?
--e.g. will they reset my "total number of searches" value so I can run my script again?

Thanks to anyone who can shed some light on this for me. Come on Google, help me out here!

==UPDATE==

Since I noticed that a few people have Googled the subject of this post, I feel I should share my observations.

There are many reasons why Google would block your IP.  Most likely, you have flagged a 'look out' protocol and they have denied you access to their interface.

The  only remedy I have found is time.  If you are blocked, just wait 24 hours and try again.  If that doesn't help you, I've got nothing.

In the future, you might want to incorporate behavior into your search queries that makes them seem more human.  I have added 'random' search instances that allow me to operate.  I can do this because my output is important--not the amount of time it takes to get the output (i.e. in Python is use the 'random' method to delay search queries).

I hope this helps.