She had stumbled over the poor bloke and ended up on the ground as well, after some spectacularly spastic movements in order to try to save one or both of them from falling. Not that Tonks wasn't used to falling, or even bringing someone down with her upon occasion, but still. "Oh, cripes! I'm sorry!"
A breath was let out, half in frustration and half in exasperated amusement. "Yanno. I should have figured that this would have happened. Shoulda been looking." A shake of coloured head given and she was popping up, holding out a hand to help the poor man up. Only then did she really process what he said. And grinned. "I reckon that I did, but I've this horrible habit of thinking that most people look like the ground. I'm getting it looked at."