PAPoots
Explorer
Only my most recent Tesa batch and the NAD+ batch I got lately have shown this. I run my finger around the edge of the cap to pull it away from the metal ring, yet roughly every second cap refuses to snap free from the lid and instead rips a little way down the side. The moment I see that start, I have to bend the cap back and forth until it separates properly. My worry is whether those few millimeters of side tearing have ruined the seal. On 1 vial I'm certain it did, since the runner plug came up — a sad day. When that happens I press the metal ring back down and hope the seal still holds. Across hundreds of other vials I've never run into this. Could be a supplier change.