Torqueflite 904 rear seal

I let a newly installed rear seal sit without driving for a couple of months. Leaked like a siv in my garage. Drove her a bit today , no more leak. Normal? Is break in needed or should she have been fluid tight from the beginning? Torqueflite 904 on a 65 valiant. Any input appreciated! Lost about half a quart is what it looked like. Thx
Author: admin