Am I worrying to much

I need someone’s opinion my 10 year old niece was talking to this man who isn’t related to us but he’s close to my sister so she considers him an uncle. Before she called him she was like can you take a picture for me so I can send this to uncle jack. Then she called him and she was like you better not talk to any woman or girls cause then I’ll whoop your butt. With a belt and he was like oh yeah ? then started laughing. I was thinking that’s inappropriate and weird so I told my grandmother. And she didn’t want me to look at the text messages she was sending him. Which was also weird to me. Am I worrying to much?

She was like I say this to my mom and youre thinking wrong etc. The other day she was sending text messages to this random little boy on tik tok talking about being gf and bf saying I love you. She lives with my grandmother and I and no one is monitoring her tablet. I can’t monitor it because I didn’t buy it. And when ever she’s with her mother on weekends she isn’t checking it either.