I don't know - I guess maybe I should have used a drip, but I've never had problems with this method before. Is there something else I should have done?
If the water they came from was fairly close to yours, then your method of acclimation should be adequate. I use the same method as you describe, except that I change out smaller amounts more frequently (using a turkey baster) and over at least a two-hour period of time. I am usually dealing with a greater degree of change in water chemistry than you were though.
I have posted a few informative links that should be easily found using the search, but I just stumbled onto an article I hadn't seen before and found it to be very well written. The information is nothing new, but it is a worthwhile read.