Why did AWS place and then refund a $1 charge on my card?

AWS has been sending notices about this kind of payment-method check. Even dormant accounts may have their default card verified, so the charge by itself doesn't necessarily mean someone accessed the account.

The same thing happened to other people with old, inactive accounts. It sounds much more like a card verification hold than an actual service charge, but checking the account and your card statement is a good precaution.

Since you haven't used the account in years, it would still be smart to sign in directly through the official AWS site, review recent activity and billing, and secure or close the account if you no longer need it. Avoid using links from unexpected messages.

That usually means AWS is validating the card attached to the account. The small charge is generally a temporary authorization hold, not a completed purchase, and it should disappear or be refunded after verification.