With the warning and a little bit of instinct, Tim manages to guide their falls somewhat so they don't end up as quite as much of a tangled mess. Which is the good part. The bad part is that then she has a second to realize who it is that just ran into her.

"...Harley."

Even if she's been assured that Harley is on 'their' side now, it doesn't make her feel any less exposed for not having her mask and voice modulator on.