iPhone electric feeling while charging

Hi everyone, I wanted to know if anyone has ever felt an electric kinda feeling in their hands while using their iPhone while it was plugged in charging? I just left that today as my daughter came up to me to feel a little bump she had on her arm. As I touched her arm I felt like a electric/ magnetic feeling as I rubbed her are and I was like do you feel that and she like no! At that moment I was like wow ok what’s going on! So I touched my son and the same thing. So I noticed that I had my phone on one hand still plugged to the outlet and touch them with the other hand and that was the cause of it MY IPHONE BEING PLUGGED UP cause when I unplugged it and touched them the feeling was gone! Why is this happening?? Should I be concerned??? All answers will be appreciated. I have a old iPhone 6 Plus but never felt this till now.