I am a 68 year old amateur who has been playing for about 2 years. I usually have two thirty minute session per day. On most days after a 3 - 4 minute warm up, I play songs that call for notes up to the G above the staff without difficulty. However some sessions inexplicably I am unable to play above the E (top space in staff). The failed attempts involve the loss of the buzz. Is it normal to have "bad emboucher days"?