Well you could try monitoring the chassis battery voltage while the engine/alternator is running to see if charging voltage from alternator is consistent. If the battery lamp only flashes while under way you could try rigging up a dash cigar lighter plug to a voltmeter.....so you can check it (voltage) while driving. Ensure no short ccts occur when doing this or you will be looking for the blown fuse next. When the light comes on you might see a major dip in charging voltage......so it could be anything such as slipping alternator belt (tensioner issue?), flaky alternator, bad connection in the alternator charge circuit etc. Visual checks might find some connection obviously loose.
At least you can tell them what you observe (if anything) if/when you take it in for warranty work.
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