Maybe you typed the url wrong. Maybe it was just an ad.
I think you're safe. If you're antivirus doesn't find anything on a full scan I wouldn't be too worried. If you are, download a bootable antivirus cd from another maker for a second opinion.
I was trying to access www.biblegateway.com Suddenly, a big red screen with printing came up, and a computerized voice said that I had a virus on my computer. I didn't click anything, but used ctrl-alt-del to get out of the window and end the task! I went to the biblegateway after this, and there seemed to be no issue. Perhaps I typed in the url wrong the first time? My virus checker never went off either. Now I don't know if I am safe.