I say find EVERY little thing wrong with the car u can, go in and have them fix it. That way if they don't fix it right then, or it turns out to be a big thing, they still gotta do it cuz the problem is from within the warranty period.
As for just giving them the car and telling them to look at it, they wont, unless you pay them. There is nothing that says they have to look over the car for free for no reason, you have to give them a reason to.