What to say to " you Gotta be more careful" ?

My partner often will say “ you gotta be careful” in an admonishing sort of way. Not once in awhile but often. I am not a careless person so when this happens it feel like he is acting like a father to me. Example— the other day I bought some cherries and rinsed him in the sink. Somehow a cherry must’ve fallen into the garbage disposal and last night he ran the disposal and it was jammed and he found a cherry pit in there. He comes into the tv room and lectures me about how I must be “more careful”.

I said I had no idea there was a cherry pit in then disposal and I would never put a cherry in there - it must have fallen in when I was rinsing cherries. He goes on and on about how I must be careful. tell him stop making a big deal out of nothing. What is the reason he does this? Anxiety ? What to say in response ?