More brake questions

Please don't scold me, although this is an 01 Century 3.1 and a cousin to the GP SE, I feel comfortable here.
The brakes on my mother's car make a small pop in the steering wheel when released, especially when in park. If I depress the brake pedal and release, I can hear and also feel a pop in the steering wheel. What would cause that? Car has 49,000 miles and never had a brake job.

Check under the dash to see if the mounting bracket for the pedals is tight. It sounds like something under the dash is binding or moving and causing the pop. I was going to suggest checking the rear drums for excessive brake dust buildup, but since it does it in park, I don't believe it's the problem.

It also does it while moving but it is much more noticeable when stopped. It feels like the condition transfers through the brakes up to the steering wheel. Kinda feels like something in the steering mechanism. I'll check under the dash and see what I can find.

Look at the bushing where the brake pedal hooks to the rod from the booster. It's possibly worn out and allowing too much free play, and therefore binding, in the pedal.