First of all 3:20 is solid. GG on that.
I’m also 41 and I’ve never had a running coach but I’ve had a physical trainer before and have had a physical therapist evaluate my running recently.
It’s 1000% worth it to have an expert help you if you can afford it. You could have been doing something totally wrong for years and they will see it. The changes you make could potentially make your efficiency skyrocket.
My experience with trainers/coaches have been all positive and beneficial.