[kh99]

Yeah, I thought you might have said "browsed back" specifically to mean that you didn't hit the back button, but I thought I'd mention it anyway. But if you use a tool that shows you what requests are being made you should be able to tell if it's being cached by the browser or not. Firefox with FireBug will show you (although it does a lot of things so it's a bit complicated). I also have used a FireFox addon called Tamper Data which does less so it might be easier to use for your purpose.

I've also heard of web servers that cache, so if you have some server settings you have access to, maybe check to see if there's anything about caching.