Funnily enough Derek , I had my red alternator light come on last Wednesday night, on a run, just for a short time, then got dimmer, then did it again a few minutes later, but not constant. Made more obvious by it being night time. I checked the alternator belt tension and it was on the upper end of being loose, so I adjusted the bracket by leverage on the alternator and engine block, and tightened up. Your bump may just have given the alternator a little movement, that needs tightening up? As an aside I have a digital voltmeter on the passenger side knee panel, so I can closely monitor charging state. I find this really useful, others have put in a USB socket that has a digital volt meter built in, which is a neat solution, but my placement means I can see it from the driving position. It told me the alternator was charging when need be. The red dash light will tell you when the alt isn’t charging at all.