Actually after sleeping (or not sleeping on it), I kind of wish I had brushed some primer in the holes on the hinge brackets before riveting them. Although I don't think it is probably really necessary, given how much the rivets expand in the holes, it would not have hurt anything and perhaps might have provided some peace of mind. Fortunately, I'll always be able to inspect them, and should be able to tell if any corrosion starts there.
In general, anything that goes someplace that will be unseen does get primed, mostly for my peace of mind.
Have you found any good brush-on primer for applications like this? (I too am not sure about alodine's effectiveness here.)
Steve