This is what it made me think of as well. My first experience with MDMA started out in the grips of anxiety, trembling and feeling multiple uncomfortable symptoms, afraid I had taken too much. I don't think I was able to even stand or walk for several long minutes.

I went on to have a wonderful & memorable experience, feeling closeness & positivity with every human interaction for hours. The worst part after I got over the initial freakout was coming back down. I've heard people talk about such early-stage freakouts happening on other psychedelics, too, but I don't have much experience there.