Web pages are zooming?

While looking at web pages, I keep zooming in??? I am not using the control key/double finger zoom method, but must be accidentally doing it some other way - and it happens quite often. If you can help, I would appreciate it. Thanks.

In Safari, command-(plus sign) will enlarge text but not the design, but if you have Zoom turned on in Universal Access, shift-command-+ will zoom in (you can tell because the page moves with the mouse).

Do you use a MacBook with a multitouch track pad? Are you placing 2 fingers on the trackpad and then sliding them apart? This will zoom.