That's such a small thing tho. It was a tiny amount and presumably they would've refunded it had it gone through. It's also possible they would've discovered it themselves soon enough, since many companies only look at the money books at the end of the month.
Also, I doubt you'd get a "reasonable explanation" from any other company - at best they'll say "sorry it was a (human|software) error, we've taken steps to ensure it won't happen again", as disclosing anything more is usually against company policy.
Yeah, that was my first thought too, but the card was already expired, and a scammer would probably have known that immediately without testing (since they presumably need the expiry date as well as the card number to charge anything).
I've had mini-charges like these from other cloud providers, too, but then I could confirm the reason for it (some sort of storage I'd missed while deleting the instances).
It matters when evaluating their response. If they said "huh, weird" for a 200$ charge I'd be suspicious, but for such a small amount, I totally see why they wouldn't bother explaining how it happened.
Also, I doubt you'd get a "reasonable explanation" from any other company - at best they'll say "sorry it was a (human|software) error, we've taken steps to ensure it won't happen again", as disclosing anything more is usually against company policy.