I know what you mean, people are always very surprised when I say I do gymnastics! I think it is quite sad that gymnastics is seen as a sport only for kids, because it is such a great sport and so much fun. I guess it is because it is very difficult, and for most sports you can kind of get away with just general aerobic fitness, whereas for gymnastics you need quite specific kinds of strength and a lot of flexibility, and most adults are not very flexible (myself included!).
The masters games are the only competition in New Zealand that has a gymnastics competition for those aged 20 and over, it is only held once a year in February (they have dozens of sports in it, for most of them you have to be over 30 or 35, gymnastics has the youngest minimum age of all the sports). There were 30 of us at the games last Feb, 12 in the advanced section and 18 in the novice section, including 5 in my age group (40 to 49) so it was great to have people to compete with, as I'm very much an exception at my gym. I did read here at CB the other day that adult gymnastics is quite big in Australia, which is cool, I wish it was more like that here!
You are lucky to have such a great coach! I'm currently trying to convince our gym to put on another coach in their adults class for the ladies who want more formal coaching rather than just free time in the gym, which is all they have at the moment.
I watched your videos, you guys are awesome! You're a lot more advanced than me, I'm only at the handstands, cartwheels and round-off level, but the great thing about gymnastics is the huge variety of different skills you can learn, so it is never boring.