Something is missing in your story. Either you're not very perceptive but there are pieces of your story that have gaps in them , thus I cannot make a logical conclusion to your matter.
I mean, so a girl you work with, thinks your flirting with her, randomly?
It sounds so utterly trivial. My question is man-to-man, just be honest (lying only hurts you), did you EVER or in any, shape or form , talk to her in a way that she might have misinterpreted as flirting?
The whole situation is so trivial anyway. Flirting; you didn't touch her inappropriate or sexually harass her and there is no proof so ...
"In the desert
I saw a creature, naked, bestial,
Who, squatting upon the ground,
Held his heart in his hands,
And ate of it.
I said, "Is it good, friend?
"It is bitter - bitter," he answered;
"But I like it
Because it is bitter,
And because it is my heart."
- Stephen Crane