We usually know so little about the potential consequences of contact with some plants or their seeds. In addition, the sensitivity of people can differ most widely. In my youth I was making camp one summer after dusk and did not realize that the bunches of leaves I collected as a base for my sleeping bag were poison ivy. I was working at the time at a place called The Malta Test Station. That was a mild reaction compared to your ordeal.
Stupidity is the reason - no lasting effects.
I guess the seeds were too young and they were trying to make me let Nature takes its course. Sometimes you don't even have to eat it to have a problem. I learned that the hard way some years ago. I weeded through an island bed of herbs, and apparently squatted while weeding in such a way that the backs of my legs rubbed all over some goat's rue plants. Very attractive and very sturdy plant, once used medicinally but no more.