Now that is the first thing I have heard of.

Perhaps, there was something surrounding you were unaware of that caused you to experience an anxiety attack?

I refuse to believe that it's possible to get a such attack by merely thinking about LDing. There gotta be something else that tricked you into thinking that your thought of LDing was the root of your attack.

For example, instead of LDing, maybe it was a fear of unknown and uncertainity that caused you to have an attack?

Just my two cents.