You may be filling it a little too much. If you tilt when filling turn it straight up a few times to make sure you are not going to the very edge or over the air tube. Even if you take it right to the edge a few drops may leak down the air tube.
Thanks, I'll try that. Do you think it has anything to do with when I unscrew the (not sure what's it's called, T3 coil?), some liquid is still on the (coil). Maybe when I screw it back on, some of it goes into the air tube? Just a thought. Do you guys wipe your (coil) before reinserting it?
EDIT: Instead of coil I meant the clearomizer head.