I've had 5 trainers over the course of 17ish years of riding, plus the occasional one ride with a different trainer or clinic with someone else. Sometimes as you grow as a rider your trainer becomes no longer the best fit for you, and at that point it makes sense to try training with someone else. I've also had to change trainers because of moving away from the area where their barn was. Give it a few lessons to see if a new trainer is a good match for you. If you don't feel super comfortable with them or their communication style isn't ideal for how you learn, try someone else.