Transmission Problem?

I have a 02 PT cruiser limited, and for a few months now, the transmission acts up a little. Sometimes (not all the time) I will be comming to a complete stop at an intersection, and the transmission will shake the car slightly, and it makes a clicking/rattling noise when slowing down to 0 and shifting back to 1st. Sometimes I go over a rough section in the road, and it will click slightly going over a bump. This isn't normal is it? Hopefully it isn't loose or nothing. Any ideas?

Thanks