Yep---switch feet and see if it still happens with the same ski on the other foot.
If not it's you ! If so it's the ski !
Pick some comfortable terrain and (in a safe way) make some medium speed turns and look to the tips to see if one flutters rapidly. If so, switch and see if it still happens on the other foot. While it could be a tuning issue it probably isn't if the same ski does it on both feet---It's a problem with the ski.