I Am A Female Aged 57 Years. I Have Been

I am a female aged 57 years. I have been exercising (cardio, weights training) for about 30+ years. I am currently a powerlifter which necessitates lifting heavy weights for multiple reps and sets, with steadily increasing loads and less volume when preparing for competition. I have noticed over the last 3 months or so that my lips go blue during sets. No other symptoms eg no breathlessness, no foggy brain and the colour comes back quickly on rest between sets. My breath is always held during a lift - this ensures a strong core during the lift. Should I be worried?