ok here's a defense for her change of plans:
She simply learned more about blood tests. Evaluating blood tests is obviously not a simple science like a pH test - this is stuff even top people don't agree on.
So let's posit she is clean. But she turns up on some list as having odd blood readings. She then learns more about the evaluation of blood tests. "Hey!" sez Paula. "This doesn't make any sense. I was clean but my blood is nutso! Maybe we shouldn't release all these names because clearly the science is not final!"
-I'm just saying that there is a logical reason other than guilt for her change of mind.