Unfortunately, I think the startle response is one of the PTSD symptoms that stays with you, for the most part. I have found that the degree to which it is active, however, varies. That is, when my PTSD in general is well-managed and I'm not having lots of intrusive or numbing symptoms, my startle is also lower. It still happens, but it is not as sensitive; so, a door slamming might set me off still but a smaller noise I might be able to manage okay.

I'm sorry you had that happen all day. The trouble with the PTSD startle is, even if you know the noise is coming, it might still scare the pants off you.