As Don wrote, it sounds like the rubber came off the bottom of the coil tower, which you can see in below and in the Post #20 video. It's not uncommon in overhead cam engines and the last time for me was doing plugs in my pickup. Unless it has a miss, I'd run the trip before risking the need to buy a new coil tower.
The Tenere's #1 plug especially has a history of collecting water and rusting down in the hole. If you do need to replace the plug, blow the hole out with compressed air, then squirt some silicone in there. Gently see if you can move the rubber boot at all with a pick to let the silicone get between the rubber and plug. Even if you can't do anything with the pick, let the silicone do it's soaking overnight. After that, you ought to be able to pry the boot off with the pick or with a mechanical finger. I've also seen where with thinner boots (not ours) the socket can then press the boot down far enough to get onto the plug flats with some pressure.
The Tenere's #1 plug especially has a history of collecting water and rusting down in the hole. If you do need to replace the plug, blow the hole out with compressed air, then squirt some silicone in there. Gently see if you can move the rubber boot at all with a pick to let the silicone get between the rubber and plug. Even if you can't do anything with the pick, let the silicone do it's soaking overnight. After that, you ought to be able to pry the boot off with the pick or with a mechanical finger. I've also seen where with thinner boots (not ours) the socket can then press the boot down far enough to get onto the plug flats with some pressure.