When you arrive home after vacation, do you check your credit card and bank statements? For that matter, do you check them while you're on vacation?
If you have a safe wifi on vacation, you can keep tabs on your activity. If not, wait until you're back home and then check. That way you can report any charges you didn't make to your bank or credit card company. They may have already called you.
Just one more reason to let them know where you are traveling, how long you'll be gone, and how to get a hold of you.