Brother of The benz, Bill
If the transmission didn't leak before your servicing it, then check what you did.
Are the drain plugs tight, both the torque convertor and the sump.
You removed the sump and renewed the gasket. The gasket could be out of position, the capscrews loose, or over tightened.
Could you have over filled the sump? This is always a problem when changing the transmission fluid. Do a close check of the level and possibly remove some fluid to eleminate this item. Better 8 ounces low than 4 too full.
Good luck,
Happy Trails Beep Beep from The Spiderman in Houston!!!