It looks fine in Firefox and Chrome. I'd still take James' suggestion seriously, as your site may have a security loophole in it.
My suggestions to complement his include:
Check for outdated plugins, making sure everything is up to date with the latest WP version.
Make sure you've changed or don't use 'admin' as the administrator's user ID. There are plugins that will help you change this if you do.
Make sure your password is complicated, and not easily discernible. There are password generator sites.
Since your site takes donations by credit card, I'd recommend using a security certificate (SSL) so that your site is trusted when processing transactions. I'm not sure how you process the info, but any site that's not secured and takes credit cards is a target for hackers.
I'm not saying your site was definitely hacked. That's a possibility, but more likely it has some security gap in a plugin. You just want to protect your site as much as possible, as we do.