how do I get across to her that her child doesn't annoy me

Well they have a 3 almost 4 yr old.  I met them when their child was 1 yr old. 

And I love this kid, I spent all last weekend playing with him. And he's little so he doesn't stop, he was constantly talking and crawling on me like a jungle gym and I was fine with it. I like kids, I work in childcare with kids his age. I had 6 siblings so I'm very used to kids.  She kept telling him "she doesn't want to play anymore, calm down. Leave her alone" and I was like hey it's okay, he's fine. He doesn't annoy me. 

And I guess she thought I was just being nice. And I can see how someone could be annoyed because he's hyper and doesn't sit still or stop talking but I genuinely don't mind him at all. 

He just talked to me all night long about how his dad took him to see air planes and monster trucks lol I mean he likes me and was happy to see me. I just want to get across that I really mean what I say lol He literally fell asleep with his head on my leg. He wore himself out 😂 and she kept saying sorry.