Ouch, that's rough, we've all been there. I too don't really stutter, it's more like I can't say the word and so I make substitutes. Most likely, however, since no one knows about your stutter as you're not open about it, no one really noticed it or would think that you stutter. It's quite hard for someone to notice unless you're purposely looking for it or if you do it consistently. Even people without speech impediments screw up what they want to say a lot of the times. Hold your head up high, this doesn't change anything. Your mind *wants* you to think that it does, as we always think of the worst outcome. You still did your job correctly, and despite the hiccup along the way, you should be proud.