Giving toddler newborns extra breast milk....

Is it weird if I want to give my 3 year old my newborns extra breast milk. Like when the bottles I store in the fridge have been in there for a few days. Instead of tossing it why not give it to my 3 year old. He’s a picky eater and one day I let him taste it in a cup to see if he likes it and he did! My husband thought I was so weird and said that I want everybody to drink my breast milk but that’s not true. I just don’t want to waste all my hard work being tethered to the pump just to throw it away. Is there even a certain age you stop giving children breast milk?