After any surgery, there is the potential for bruising which is simply bleeding under the skin. That's what causes the discoloration of your skin. This is very common after liposuction, is usually self limiting and gradually resolves over 2-3 weeks. Compression garments, iced compresses and gentle ambulation will help speed dissipation of the bruises. Follow up with your plastic surgeon so your progress can followed and be patient.
Bruising is normal after liposuction. How much is normal can depend upon many factors. If you are concerned, you should see your doctor.