Replace ABS brake actuator before throwing code?

I have a 2011 Prius that is making the buzzing sound from the brake assist system ever 20 seconds when parked. After posting about it on here, I became concerned it was on a verge of failure and brought it in to a hybrid specialist mechanic. They assured me I was being preemptive and seem very reluctant to tell me that this repeating sound is an issue or that there’s anything wrong with the brake system. I’m confused because he claims that he is not hearing the noise (since noticing it over a month ago it has never NOT made the buzz every 20 seconds) and that because there are no codes, everything is fine. However he did mention when I first dropped it off that if it is making that noise it does mean that it will eventually fail. So that seems confusing. I still felt like I couldn’t get a clear answer on if he felt like I should not replace the actuator yet because the noise is not a sign of imminent failure, or because he just didn’t hear it (which would be because it’s difficult to hear over the noises of a loud shop) and NOT purely because the noise is okay.
His advice is that I can have them replace it if I really want to but he doesn’t think I need to. Which makes me just feel silly even considering forcing a $1500 issue if it really is fine.

I don’t want to create problems where there are none- but can someone just tell me if the brakes are supposed to be buzzing so often and if not, does this mean they actuator is failing or not?!

I’m about to drive across the country alone, and plan to sleep in my Prius often- this was the only good time to bring it for a major repare, it would be super unfortunate for the system to fail out while I’m traveling….

 

it has 104k miles, and has a clean bill of health otherwise.