Hi (hidden)-

I spoke with our tech support team this morning, and they were able to point out that in this case, the "example A" ad is showing because the "example b" adgroup is reaching its campaign budget limit. So, because this campaign is spending up to its cap, when one of its ads would normally show, the system is forced to choose an alternative, so it shows an ad for the next best performing keyword in the account.

This particular time that you saw the " example A " ad showing, it was because the campaign that contained "example B" had maxed out, and the system picked the next-best term in the account (which was one from the example A).

If you'd like for this to stop happening, I'd suggest increasing the daily budget for this Campaign. Please let me know if this doesn't answer your question, or if there's anything else I can do to help!