It doesn't matter if you approach from behind. What matters is how you do it.

When you tap her or call her to turn around, you can't be in her face. Sometimes you forget because you've trained yourself to close distance though.

When this happens she'll tighten up a bit but I've never had a girl lock up from this, as usual you pop back out, and make it known you know she's a little freaked. I like simply making a facial expression for this. What you can't wink you gesture, what you can't gesture you say, what you can't say you write. 'Brevity is the soul of wit'.

Then usually she'll giggle and relax, you can pop back in and game as usual. Heavily field tested.