Kissing and a cold sore

nicademus20

My boyfriend has a cold sore that comes and goes as they do since he was 7 years old. 
He got it from his mom. 
We recently visited his family for Christmas and as we were leaving to go back home, his mom gave a quick peck on the mouth to my little baby, her first Grandson. I saw it, side profile, right infront of me.
I got mad because I don't want my little one getting a cold sore he'll have to deal with on/off for life! 

But I didn't say anything. 
I didn't see any visible one, but what if she had when it could have been passed like she did with her own son? 
Quick pecks on the mouth with a cold sore can still pass..
My boyfriend says I shouldn't say anything, and he refuses to say anything. 

Maybe wait until one is visible when we visit and say "no kisses on the mouth to your Grandson" then?