Should I have said something?

👑G

So let me start of by saying if this is in the wrong group, I'm sorry let me know where to move it & if what I say upsets you, again I'm sorry. Okay so on Saturday me & my son went with my mom to the Volkswagen dealership to take my grandpa's car to have the routine maintenance. We got there before 10 (we had a 10am appt) and it was about 1030 before they checked us in and let us know it would take 2 - 2 1/2 hrs... 🙄🙄 Anyway we just stayed in the waiting area and tried to distract my son since we would be there awhile (he's 3). Sometime after 1pm a lady with her daughter came in, my son this whole time had been playing on his tablet or looking through the magazines they had on the center table. Well he sees this little girl & he's excited to have another kid to play with. So he starts showing her the magazines (she's at least 5 or 6) and she just grabs a few & takes them to sit next to her mom & my son does the same. When he see her get back up for a different magazine he jumps up real quick & hands her the one he has, grabs another & comes to sit with me. This little girl goes and takes every magazine off the table pit them on the chair next to her mom & stands in front with her arms crossed looking over at us. (the mom isn't paying attention, she's been on her phone the entire time) My son is super innocent and doesn't realize what this little girl is doing, he even takes the last magazine he has & puts in on the table, & the little girl came real quick & grabbed it. She again stands in front of her chair arms crossed blocking all the magazines from my son. I have never seen a child that young with RBF (resting bitch face), she stood there just glaring at my son. By this time the mom notices but says nothing. (she was stuck up anyways) I just stayed staring at the mom waiting for her to say something, my mom could see I was pissed & just asked me not to say anything cuz we were about to leave. It was after 2 when we finally got the car keys back to leave and as soon as we got up to leave the little girl put back everything. Should I have said something to the mother? Or should I of told the little girl to share? Or did I do the right thing by not saying anything? My son has never been around adults or kids like that, & he has such a good heart & is always trying to share everything he has. I mean even after she took everything he was trying to show her his tablet (the little girl just ignored him). Sorry it was so long but what are your opinions ladies? what would you have done?