I recently had the same problem. in my case I had the converter goand the vibration caused the bushing to go and then the seal. you do need to pull the trans to replace the seal. however if you do end up needing to replace the bushing you will need to pull the front pump out and split it to push it out. It is relatively inexpensive fix if you do it yourself and I would hate to see what a shop would carge you to fix it.