It happens. Candy Japan gets a bit of discussion here on HN, and has a few posts about credit card fraud on the blog (eg https://www.candyjapan.com/behind-the-scenes/how-i-got-credi...). The basic premise is that credit card fraudsters use small online transactions to check if a card is valid before they use it for the big high value stuff, and the cost of those transactions to a small business can make it expensive to run.

That said, if you're just enabling features on a site the actual cost to you is effectively zero, so maybe it's not something to worry about.