crying 13year old

HI,
My nephew is visiting from Germany. He shows almost all the symptoms of LD as described on this site (not reading, not remembering what was said, writing at kindergarten level, holding pen with wrist, etc...). But I was very puzzeled today, when I tried out something. After having been in California for only 2 days, and seeing the moutain from the northfacing side only a couple of times, he was able to recognize (and was certain of himself) this mountain from the south-facing side before even his granddad could. He told us, it's easy, he just imagins the mountains other side and it was our mountain. Admittedly it's got a distinctive look, but this is not the first time he shows that he has almost photographic memory and 3D skills. We try to write with him daily and so I tried to let him write mirror reverse. For fun, really. Thinking he might shine and enjoy it and gain a sense of success. He did really well, but started to cry intensly. I'm not sure why. We put NO pressure on him. We were very positive, gave him time and explained that it's just a fun thing that most adults can't even do. I'd really appreciate if any of you have similar experiences and what you think might be the cause and if you have any recommendations as to weather or not we were actually opening up a path somehow, or a past trauma, or if we should stay away from stressing him like this. I just want to help.

In Germany, he has been tested but was not diagnosed with any LD. He is attending a special school for disabled (most severely) children. But receives no LD specific teaching/attention.

I think it is something that were in his small age