First let me give you the background. Recently I have become a lead trumpet player for my high school jazz band. My first task, obviously, was to work my range up to par for the charts that I had to play. I did lots of lip slurs, long tones, and practicing the high notes that were in my music. This helped me a lot short term, my range went from a weak high Eb at the beginning of the year to a strong high G/A and occasional double C by the end. Soon after the school year ended, my range and endurance went down a LOT. After talking with my teacher and director, it was agreed that this was due to a problem of mouthpiece pressure overuse, which stemmed from me playing too much high notes without proper technique and straining my embouchure. So I spent almost a full month just practicing things like clarke studies and playing slow tunes at a soft volume, striving to improve my tone and make me able to relax. After I got the hang of this, I started doing my lip slurs and high arpeggios (range exercises) again, this time using proper form and not tensing my embouchure. My range has come back fast, within a week of doing these exercises I had gone from barely a high D (yes, I lost that much range) to getting my solid G's back and screaming loud F's. Now I notice that when I play anything high, my corners involuntarily stretch, like a smile. This only happens in the extreme upper register, and when I play a phrase that starts high and then goes lower, my corners go back to normal as I go back down. I've heard this is a bad thing, and although my corners aren't stretching into a full smile, they're noticeably stretched. My pressure problem seems to have gone away, I never experience lip pain, swelling, or poor tone anymore. Is this a problem? If so, what does it mean/how can I fix it? (My trumpet teacher is coming back in a week and a half but I wanted some other opinions first).