What would I do? Feel flattered that they used it?

To be honest I don't think there is practically much more you can do other than what you have.

I have a few photos that are used in various places without consent and .they have given no attribution or acknowledgement e.g. on commercial travel sites, a US politician's web site (and I disagree with their politics) and even church web sites. There are also quite a few that have asked for permission and do give credit

Unfortunately if you put it out on the web, it will get used and there isn't much you can do.