I had a very similar situation at my work last year. I asked a question after my colleague gave a presentation and really struggled to get my words out. It was awful, as I had never disclosed my stammer to my colleagues, and it’s fairly rare nowadays so they’d never noticed. I sent an email to my group and everyone was incredibly supportive. Ever since then I’ve never worried about talking in front of my peers, and the reduction in anxiety has had a knock on positive effect on my fluency… so it’s a win win! Your boss will appreciate you telling them. Go for it for you!