Since it's quiet here, I thought I'd ask another question about this. To you, does a pasada (step over) imply a parada (stop or pause)?
What are other's thoughts on this? Does a pasada imply a pause for you? I know I've seen others (although not often), do pasadas without a pause before stepping over.
This is really just a slight variation of the same question, isn't it? Since your chest kept going, you were
leading the timing of the stepover. She either expected a pause (and then you would lead the pasada) or she didn't really expect you to lead the pasada at all and is subconsciously expecting to do it in her own time.
I would reiterate that if there is no pause for her to make contact with the leader's leg and realize she has to step over it, then the timing and placement of the leader's leg has to be
impeccable. Otherwise it becomes a tripover. It becomes like doing a sacada to the reaching foot instead of the trailing foot just as she's about to transfer some weight to it. Oops... sorry.

Sacadas don't work that way.
The stepover has to happen while she is still
solid on her standing leg, not in the middle of the weight transfer... .ie: at the
beginning of her reach.
Remember that the follower is instructed to keep her free reaching foot in ever so slight contact with the floor. Therefore, she's going to have to purposefully lift it to get over your foot. If there is no pause from you, she has a split second of time to realize she has to
raise her foot AFTER she registers the info that your leg is in her path to accomplish this without stopping. And if you think about the construction of people's feet, the top of the foot has formed a hook under your leg which slows down the "getting it over" part. This geometry is not as big a problem in a sacada when her leg that's being displaced is behind her.
I think it's entirely do'able for the pasada to be led without a pause, but I suspect it's an advanced skill to get it working smoothly with someone who is not accustomed to you as a leader or this particualr way of leading it.
I would also point out that the follower's technique needs to be pretty impeccable as well, so that she has not started transfering weight to her reaching foot too soon... that makes the tripping more likely. But keep in mind that since she is to have her weight forward, and she's likely to be wearing heels, the amount of forward reach she has
without placing any weight on that foot is:
not very much.
I'd also add, that the way most people I've danced with lead the pasada, it's actually the big pivot around (on my right leg after the forward ocho to his right) that clues me in to the fact that I'm probably going to be stepping over his leg on my next step, whether or not there's much pause. And yes, I've stepped over legs that weren't there. But it's better than being tripped.