new 2007 sorento owner, so far so good but a concern, knocking

well, we really love our new sorento. have about 5k miles on her now. one thing that kind of bothers us though is, when you pull off from a stop, there is a knocking that you can hear. it sounds like it's from passenger side in the middle of the car. its not always but i noticed it is more prevalent when i have 4 or 5 adults in it. maybe some kind of suspension knocking but don't know. has anyone heard of this? these are always hard because if it doesn't duplicate when we take it in, makes it tough. thanks for any insights.