Part of standard operating procedure where charging problems are evident, but it appars the adapter itself is working, is to suspect the System management Controller is at fault. In many cases, resetting the controller restores functioning.
Thanks, this seems to have worked, and the charger has been working fine the past couple of days. Curious though, what is the SMC and what does it do? I read the Apple Tech article, but it doesn't say much in terms of what exactly it is.
In addition, are there actions I can take to avoid this issue again in the future?
The SMC is a chip in the computer that manages the power in the computer by monitoring and controling various hardware components (backlights, fans, battery charging, that little led that flashes slowly on Macbook Pros when they are asleep, etc). My guess is that it is an Apple-specific chip. You can think of it like a special-purpose, low-power CPU. See this article for a bit more info about the SMC.
I don't think there is anything you can do to avoid it happening again - problems of this sort seem to happen occasionally. Apple releases updates to the SMC code every once in a while when they identify problems and come up with a fix. If you notice the same sort of problems again - reset the SMC and see if that fixes it.