A couple of days ago, I came home to find that I had received a call from the security department of my credit card provider. I panicked a bit, of course, but called them straight away. They told me that they had flagged up a couple of transactions as suspicious, and gave me the details of the dodgy items. To my great relief, the transactions had actually been made by me, so there was no problem.
I have no idea why those particular transactions were seen as suspicious, but I'd certainly rather have a few false positives than for them to miss genuinely fraudulent transactions. I was also quite impressed that they phoned me to check. However, the whole experience did feel a little bit like my Mum reading my credit card statement and pointing out items in a slightly disapproving way: "Now, this one here -- did you really need to buy that, it was rather pricey. And this one, what was that for?"