Punctuating. When is speech not speech?

Question

I need help to punctuate the following correctly. I was told I need to punctuate the woods words as speech? I would have thought that it was more like an echo rather than direct speech.

She thought she heard footfalls behind her. She stopped and listened; all she heard was the thud of her heart beating.

'Just stop it,' she scalded herself aloud. 'You're being paranoid.'

Paranoid... the woods whispered back to her.

She spun around wildly peering into the undergrowth.

Answer 1

Argue your side to your instructor, most teachers will listen some will take into count what you think.  but if the woods are whispering back it does need punctuation

Answer 2

I find it understandable as you have punctuated it, but I think it strains too hard after effect.

Here is another way to do it:

She thought she heard footfalls behind her. She stopped to listen: all she heard was her heart beating.

"Stop it." Her voice sounded louder than she intended. "You're acting paranoid."

"Paranoid," the woods repeated.

She spun around, peering into the undergrowth.