ipad screen flickering when scrolling

I recently bought an Air 2 after getting advice on this forum. I'm loving it so far apart from one niggle, sometimes when scrolling down websites the screen flickers/stutters for a few seconds. This has happened on both Chrome and Safari, a couple of times a day and seems to be on certain websites. I am just wondering if anyone else has encountered this and if it is normal or if there is a fault with my ipad. It is a refurb. I'm currently still within the 14 day return window so if it is faulty would rather take it back soon.