At my first appointment they got to the question about food and I said I like all food I dont have an issue with food, but I dont like my wet food touching my dry food, and got into a discussion about how pasta is a wet food but rice is a dry food, however if its rice with curry then rice isn't a food at all, its a barrier, and it protects my other dry food from getting wet.
We also talked about my gardening hobby and how I love to grow tomatoes and this stems back to childhood where I had a pet tomato I carried everywhere until it rot beyond comprehension. My emotional attachment to it was intense, and even now I know an awful lot about hundreds of varieties of tomatoes. Gardening is a perfectly normal hobby. I dont know much about many other plants though, I have to casually learn as I go, but tomatoes... well I could write a book or 3.
Basically what they're looking for is proof that your perfectly normal things are abnormal to other people in frequency and intensity.
To me, watching planes and trains are categorically boring. You'd not catch me watching trains or planes for fun, I would go with a friend if they wanted to, and I can vaguely see the interest, but if I had to participate it would be occasional and wouldn't be something that would take up most to all of my free time. To me, going to see planes and trains especially alone, or tracking them, is abnormal in frequency and intensity, although that isn't a criticism of the hobby itself and I think it's exceptionally healthy to have hobbies and know exactly what it is you like or that brings you happiness and joy.
So although it does sound like a negative criticism from them, they've got to be strictly clinical and that can sound like they're pulling your perfectly valid sources of happiness apart.