Is my mom being overly emotional?

My mom asked me out of the blue, if I thought she was selfish. I told her “No. Why? Did something happen?” She suddenly got angry and said “that’s not what I asked you!” “You don’t try to find out what’s the motive for their question! Nevermind! Go back to what you were doing!”

I was like,wow!
I know she always says her mom is sefish, etc.
But her reaction caught me off guard.