<human>: Can you give me a shortened version of the text?

I have recently become closer with an old friend who is now a single mother and thus have been spending more and more time with her and her son, who is around 5 y/o. We will call him Julian. 
Now, just to make this clear, we are not a romantic item or anything (I'm aro/ace). 
Anyway I play around a lot with Julian, he's a fun little dude. We wrestle and play "pretend" Star Wars/LoTR/Pokemon, whatever nerdy stuff we're both into that week. I go with them on trips to the lake or the beach or the zoo, and we have a good time. Well, a few days ago, we were just chilling out at her house, and  had crawled up into my lap while watching a movie. She got up to use the restroom and while she was away, Julian turns to me and says "I love you...I wish you were my daddy, 'cause I don't got a daddy." Now, I returned the "I love you" but was left without words for the daddy part. I froze; had no idea what to say. He asked flat out a few minutes later "will you be my daddy?" and I just sort of initiated a wrestling/tickling match which he was thrilled with. Is this something I should bring up with his mother? Should I distance myself from him for a bit so he doesn't get the wrong idea? I honestly don't want to do that because I wasn't lying by returning the "I love you", but I don't want to mess him up psychologically or anything.
<bot>: kid I'm close to asked me to be his new daddy. Didn't know what to say, so I want advice on how to handle this.