It seems to me that this is a female. You would definatly know if it was a male from the spurs- they are not difficult to spot.
Because it is a female, in my opinion you need to start your research NOW on what happens when she is ready to lay eggs. Even if she has not been bred, she will lay an infertle clutch.
PLEASE PLEASE PLEASE do as much homework as you can now, instead of waiting for the last minute and posting that your cham wont eat and is walking around on the bottom of the cage. I understand that you thought you were getting a male, and im sorry that the idiot at petco told you otherwise, but a female chameleon is just about the most difficult pet to own in my opinion.
There are about 5 zillion threads about it on this forum, almost 100% of them are the exact same response and story as the next.
Best of luck with your new friend, be careful, they are addictive!