Is Pyramid Head's (and I guess terror radius in general) bugged?

RoMainPuppy

I know he has that one perk that can make him undetectable, but I swear that I think there are times he's not using it/hasn't used it and yet the terror radius doesn't trigger until he's right against my ass.

Same with a couple other killers lately. I know there have been a lot of sound bugs lately, is this one of them?