Sure it can happen to anyone, I suppose. I’ve had two lesson requests rejected (not the same one twice) — two different teachers (actually, "community tutors"). They explained that the time was inconvenient, yet I had simply selected a time from the schedules that they had established. I never made another attempt to book a lesson with either of them again — obviously. Whether or not the explanations were bogus, I just don’t need to deal with teachers who don’t set up their schedules properly. No big deal — there are plenty of teachers here for us to choose from.
As far as a teacher who has already had a lesson with you and rejects subsequent requests with no explanation… you asked a question, so I'm not going to lie to you or beat around the bush. If she wanted you as a student, she’d probably give you an explanation and invite you to choose another time. If she didn’t want you as a student, she might also give you an explanation, but it would be nonsense. You don’t really expect her to tell you that she didn’t like teaching you, do you? If she intended to give you an explanation, she would, so “kindly ask[ing] them” is not really cool. in any event, do you actually want to take lessons from from a teacher who rejects your lesson requests with no explanation? Like I said, there are plenty of teachers for us to choose from, so you might as well find one who likes you, wouldn’t you agree? Keep looking, and I'm sure you find the perfect teacher (or teachers) for you.