I am terrible at reading body language, but to me it seemed like JT was indeed 'stripped' of the captaincy (i.e., this wasn't his decision, it was management's).
But I'm not worried about it either. JT knows how things work in this market, he knows that Matthews is the face of the team, and he does not strike me as the type to get embittered over something like this.
As others have said, it was probably inevitable, too: A bit surprised that the Leafs decided to do it this summer instead of next, but Matthews was always going to be the next captain.