I called Go Solar and verified that, because I didn't know either. You might be OK as long as you didn't leave it connected too long, which would have eventually overheated and boiled a flooded batt. I don't know the effect on AGM. I'd be more concerned about frying the Go Solar controller with the higher voltage. Does controller seem ok now?
BTW, your last sentence confused me, there is no such thing as 100W AGM, the panel is 100W. Assuming you meant 12v AGM.
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