Yeah maybe that too. Sometimes, hackers will be nice enough to tell you what they did, how they did it and why they could do it, then tell you to fix your site as soon as possible in case it happens again. These hackers are malicious too and usually you have to report them too, since they are not allowed to abuse security of websites, but at least they're a bit better than the ones who just wreck the site and go away
EVen worse are those who setup code on your site through exploits and upload bad files that either infects people or spam people from your own email address then get your hosting account suspended or even banned. This happened to TIMGUL in January 2008 (quite ironically, this happened not long after Omni shut down and not long before the anon raid on Omni temp board)