I would say it's very common. Our gym does Xcel instead of levels 3-5, but our bronze girls are typically training squat ons, flyaways and kips, silvers train flyaways and kips as well as baby giants, clear hips, etc. Golds start training giants on the strap bar. It's pretty typical to see girls up training skills that are anywhere from 1-3 levels above what they are competing. This can differ widely by gym of course, some gyms do little to no up training.
I will admit I was surprised too to see my dd learning flyaways, etc in bronze. And a little nervous. But usually the higher level skills are very heavily spotted at first, and done over proper matting or a pit. I think they like to introduce them early b/c once a skill is introduced it can take quite a while to be consistent. Fear, mental blocks, etc can kick on on a more scary skill like a flyaway. My dd had hers, but is now scared to do it. Luckily since they introduced it early, she still has a year or maybe even longer before she needs it for competition. There is also benefit in introducing more scary skills when they are young, the younger they are, usually the more fearless they are.