Misattribution of arousal: a psychological occurance where people (and ponies) may take the attributes of one emotion (fear: fast heart rate and breathing) and subconsciously associate them with another (arrousal: fast heart rate and breathing). Therefore, Octavia may subconsciously misattribute her fear as attraction to Vinyl. Also, she just wants someone to comfort her. Vinyl you sly dog.
So this was her cunning plan. I say its very cunning, as cunning as a fox who graudated top of his class in cunning then got a job at the minstrr of cunning and soon became head of the cunning department