Transmission fluid coming out of the transmission stick, Help??

I have a 98 mazda 626, 4 door, lx, with 150,000 miles..I just replaced the transmission and it drives and shifts great... but I am getting transmission fluid coming back out of the transmission dipstick.. what is causing that? and what should I do????

Maybe they, after putting in a new transmission, overfilled it, and now when the transmission is running it wants to get rid of that excess oil.

Sounds like an overfill. What happens sometimes is that they forget to drain the torque converter and then fill the transmission to spec based on capacity (which means with an empty TC). I'd take it back and complain.