12.4V sounds a little low for the battery charge. For a sealed AGM battery I would be looking at more like 12.8 to 12.9V. I'd certainly get it fully charged as a first step and then monitor to see how it's holding that charge and/or if that resolves the warning light.
Thanks. Just living with it for now until a) the battery gets bad enough that other things start showing up and i then HAVE to change it, b) I need to get rid of the warning light before trading it in.
Would go for option b right now if I did not need to front the wife !