I’ve experienced unintentional vibrato when being put on the spot for a tuning note, only to be able to play it perfectly fine at home. I’ve also had playing situations where I was totally in the zone, playing in front of a mic in front of the band. Unfortunately, my discomfort with certain playing situations and the physical response to these built up a pattern of extreme tension, which eventually seeped into my playing and practice. I’m working on rewiring now. This involves a complete teardown of playing psychology in favor of a healthier mindset to develop new neural pathways, along with paying close attention to triggers and finding ways to reinforce more efficient playing. Personally, I suspect that there is a strong link between focal dystonia and performance anxiety/perfectionism. When they are both present, they feed each other like crazy. Look closely at Greg’s playing psychology. It’s deep and part of the path. What you’re describing could be the beginning of a dystonic pattern, but I’m no expert. Patterns can be changed with focus and effort.