Mine did this. You DO NOT have to pull the trans, but you need a special tool that looks like a deep well socket to remove the old seal. The shifter shaft seal is out, it cost a whopping $2.00, but if you dont have the tool, you'll have to bring it in to a tranny shop for them to remove the old seal and replace the new one.
Of course, every shop I found had a minimum of $75 which included an "inspection" -but we all know what that meant. By the time they added taxes and general b.s.- it was $100.
See if you can rent the tool urself, I couldnt find one to rent nor buy.
The tranny shop will have the seal, some auto parts stores carry them. Good luck.