Wolf tooth?

We lunged Remy this morning, fully tacked up with cavesson, bridle and saddle.
I walked him around for a few minutes on each rein to warm him up and then tried the trot on each rein, both around the school and on the circle.
There was no sign of any nodding and both Jim and I thought he looked completely sound.
I then mounted and we did the same with me onboard. The first time with no contact, the reins resting on his neck. He was fine and no sign of nodding after the transition to walk.
The second time, I took the reins and had a light contact and we noticed a slight raising of his head after the transition to walk. I was careful to give the rein immediately after the transition and although it was only slight, it was still there for a couple of strides.
So, we think (hope) that it may be discomfort in his mouth, perhaps with the unerupted wolf tooth, or even expecting pain. He's very soft and responsive in his mouth, but also, he's always been very sensitive and aware of the bit, so perhaps he's not really too comfortable with it.
I'm going to continue to ride him, with the bit in his mouth, but the reins attached to the cavesson to see how he goes, and perhaps look to changing to a light rubber/plastic bit, although I have very little knowledge of this type of bit.
I need to speak to peter, our equine dentist as it may be best to remove both the erupted and the blind wolf tooth.
We'll see!
On reflection, the thing that really surprised me yesterday, was how well he went when I rode him off the cavesson. The feel was different in my hand, but his response was the same. We did some trot and a shoulder-in on each rein and he coped fine.
I have no knowledge of riding bitless either, so this will be interesting.