I have been masturbating for more than 60 years, several times (depending on my age, anywhere from 3 to 12) a week, every week since I started. When a person masturbates that much, YES, you are going to be seen masturbating.
I have been seen by my partner, mother, cousin, several friends and possibly more.
Also, note that I did not say caught. Caught implies that I did something wrong. Masturbation is not wrong, therefore I call it being seen.