From what I understand of your story, don't think there is any reason to be worried. Annoyingly, having a block once or twice with a specific word can turn into a habit *very* quickly due to association, the more you do this, the harder it gets to break out of this pattern. For me it helps a lot to speak to myself in front of the mirror, trying to use words that i find difficult to pronounce IRL - if i stammer on a specific word in front of the mirror, i can get through the block fairly quickly. practicing like this helps me to loosen up or even "unlearn" specific blocks