Didn't put the whole can in? I always do. And yes, if you turned good fluid bad, thats a very good thing, but that also means you should have changed it twice. About 100 miles before you change it again, it probably wouldn't hurt to add in the other half of the trans tune.
I always change my fluid twice and filter once when I do my fluid. Wakes the transmission right up.
So hows it doing as far as drivability in comparison now?
Also, I noticed you changed the pan gasket....Were you not able to reuse the one that was on the transmission? Or was it cracked?
What did you replace it with? I hope it was not cork. Rubber is about the only recommended replacement, and the GM one is even better. If you did replace it with cork, put on a GM one next time you drop the pan.