Am I a victim of csa?

I don't know if this counts as CSA, or rather, I haven't come to terms with it yet because it's a memory I only recently had resurface this past week.

If people could give me very objective answers before stating any subjective comments, that would be very appreciated. My brain works better on knowing something is fact.

For context: I am currently in my mid 20s, an Asian-American immigrant, and diagnosed autistic.

When I was 8 years old, my grandmother visited my family from across the country and stayed at our place for about a month. During her time there, she would have me take showers with her and during one of them she asked if I would suck on her nipples. Like a baby wanting milk. I did, not knowing any better, and then she told me that nothing was coming out so I should try her other breast.

That's all I remember. Nobody in my life knows this happened to this day- hell, I myself only just remember. My brain is short circuiting trying to process this as it keeps going back and forth of "well it only happened once", "it was so long ago", "people have been through worse", "it was your own fault for listening to her", etc. I don't know what to do. I don't know what to think. I'm scared to call myself a victim of anything because what if I'm not? What if I'm blowing this out of proportion? Is this CSA? Is it not? How do I even begin to process this if it is?

Please help me.