It happens all the time. I opened my lid and noticed after all that "loss" it still took 20 seconds to see the meat in there. I then quit worrying about it...figured there was plenty of smoke to still go around.
Did you mean you can see smoke coming out from under the lid rim while smoking?
On a new WSM, smoke leaks are not too worrisome in that the more you smoke, the more the gaps get filled with smoke residue and the leaks seal themselves. With 10 smokes on the WSM, you now should be able to close top and bottom vents to put the WSM out(save charcoal for future smokes). If you can't put out the charcoal, the leaks are probably too big and they'll need a little tweaking.