I have a multipage form which works largely by posting the form details in query strings to the url. I know this isn't ideal and i've already changed it.However, what was happening is that google was caching results such asmysite.com/myform?var=var&var2=var2&var3=var3Where the var(s) were populated with form submitted form details.Any idea why/how this is happening?  Thanks in anticpation. 
Google has cached query string based dynamic page, but how/why?
cache;url;google
It's possible that someone posted a link to it with the values embedded. Google may also submit simple forms in some circumstances.