MIL keeps feeding my son every time he cries

So since I've been back to work, my MIL watches him. He's about 3.5 months now. She told me yesterday she gave him 10 oz over the course of 45 minutes. She says he didn't spit up much afterwards. We usually do 6 oz a feeding, but sometimes an extra 2oz if he's still hungry. I also mainly breastfeed him so not entirely sure how much he actually gets there. But she seems to think everytime he cries that he's hungry. I just think 10 oz is a lot but what are your babies eating?

Am I overthinking it or should I say something to her?