Alternator Failure

[sscaro]

Yesterday the red battery icon lit while driving. I made it home & hooked up my battery charger to make sure I would get to the shop the next morning - my charger is one of those that charges until full and then goes into "top up" mode. It also has an alternator test, which tested the alternator as good after the battery was charged.

This morning I started the X and there was no battery light. I went to my indie shop and he said that the alternator is the only thing that will trigger that light. He also said that even though the light went out, the fact that it went on in the first place means there is a problem, and we can't know when it would reoccur - he recommended a replacement to avoid failure at an inopprtune time.

I went ahead & replaced it, but wondered what you guys think about his assessment - I've known him a while and have always thought him trustworthy.

Did I do the right thing?