Happening all the time with me, but it’s down to slight delays loading in, and pages jumping around as the ads fill out the template. I often go to click/type and an ad spawns under my finger.
Yes, I know this is deliberate to irritate me into...
No mate nothing should pop up, not had that - unless your clicking/hovering for a while over an ad. If it happens again please nab screenshot so can report it.