Self conscious

Me And my boyfriend were talking earlier and I said something and he paused and said "can I say something that might make you feel self conscious?" I told him no because the last time he said something like that he said that his fingers smelt after he fingered me ( he didn't wash his hands afterwards :/) and now the curiosity is eating away at me. I want to know what he was gonna say but I don't want me self confidence to be shot down again... 
Should we be this open about stuff like that? Like I don't tell him his dick tastes & smells gross?