Lol, with how much Agnes LOVES you, I doubt she even gave it a second thought. Though I'm sure she wouldn't refuse a treat if you offered it as an apology, hahaha. She was probably more like 'what in the heck was that' and didn't even realize it was your foot that did it. I've also had rabbits do little squeeks, and I think that's what you most likely heard from her. Trust me, if she had done the death scream, there would be no doubt in your mind. It's very unmistakable.
Leashes actually work pretty well. I've used a leash for years, and this is the only rabbit that has ever done this. You also kind of get the hang of how best to use it too. Like if I notice my rabbit is getting scared of something, then I'll kneel down next to the rabbit to help calm it down, or if it's freaking out about something, I'll shorten the leash, to get to the rabbit, then scoop it up and hold it close til it calms down. I will mention that if you get one, make sure it has one of those stretchy leashes. It helps to have that little bit of 'give' in the leash when your rabbit decides it wants to suddenly dash off. You also kind of learn to use your arm to give a little too, so that there isn't a sudden jerk on the leash with your rabbit.