There probably is a better way to explain it, but here we go:
When I use my laptop's touchpad to scroll up/down, and then press ctrl (typically to switch between tabs with ctrl+tab), the browser interpret this as "zoom up/down" (since you can zoom by holding ctrl and scrolling). This happens even when the top/bottom of the page has been reached for a few seconds, presumably because the scrolling motion "stick" a bit after you stop your gesture.
This is a rather annoying behavior, and I wonder if there is a way to stop it. The only thing I can do in the touchpad's settings is to disable scrolling entirely, which is a bit overkill. Any idea?