Little boys exposed themselves to my daughter

It’s normal. I know. 4 year old boys are very aware of their penises. For some it’s a handle or a go-button. I taught preschool. I get it. Can’t count how many times I had to say “get your hands out of your pants!” What I’m not cool with is the 2 little boys who exposed themselves to my 4 year old daughter. Out of the blue yesterday she asked for the correct names for boy and girl parts (we’ve had the safe touches talk a few times). So my brain started mulling on how random that was. Today I asked her if the little boys in her class had been talking about their penises. She said yes and then turned away from me so she couldn’t look me in the eye. Red flag! I asked if any boys had shown her theirs and if she had shown her vagina. She could tell me every detail of the moment. Where she was in the classroom, what dress she was wearing, who the boys were...and the worst part was the shame she felt. She didn’t show her vagina, but she said she was afraid SHE would get in trouble. Which is why she didn’t tell her teachers. Some advice on how to handle this would be appreciated. 😞