ATF oil, fork oil, whatever oil..........if they leaked it's either down to the seals or the fork stanchions themselves. Are the stanchions pitted? If so, the oil will get into the pits and then leak past the seals, and the pits will also eventually damage the seals.
Red has a good point if you have over filled the forks then the oil will try to find somewhere to go and could start to leak and possibly damage your nice new seals.
Yes, it has been known for people to fill the forks brim-full with oil, then wonder why they seem somewhat solid ! There is a specified volume of oil in them, (or on much more recent models, filled up to a certain distance from the fork top).
When forks leak a few months after a rebuild I've often found the cause to be a bend in the stanchion. The seal can cope for a while but the increased side loading gradually causes it to fail. It doesn't take much of a bend for it to happen either.