Back when I was younger, I used to make fun of my cousin who had a serious problem on people who held her baby. She was too scared of germs that she wouldn't let us touch her baby.
Now that I'm a mother, I got a little bit scared to touch other people's baby in the mall (I did that all the time before). I wouldn't want the mother/father to feel uncomfortable.
As for my baby, I wouldn't mind people touching her, I took it as a compliment. But I realized now that every mother has a different thing that they are not comfortable about.
For me, recently I just discovered that I am not comfortable with people giving food/drink to my baby without my permission.
I know it's cute to give food to baby, and I wouldn't mind if you want to feed my baby, just that it would be respectful for you to ask. By saying "I wouldn't mind" does not mean I'm okay with you giving my baby junk food or anything weird.
I am VERY particular on what goes in into my baby's mouth.
I am glad though that every single time I did not approve what goes into my baby's mouth, she would vomit it back :)