I just got a used 2003 Galant ES and I've noticed something that worries me a bit. At about 30-40 mph I get a gentle kick about 50% of the time. It is not a harsh bump, but just a slight one as if you go over a crack in the road. The car has about 65k miles on it. Is this something I should be very worried about?

I didn't purchase the car. My brother did for me and he said it was sold as is, so I'm hoping the costs aren't adding up only a few days after getting the car.

Thanks for any info or suggestions.