What you should do is not share a spoon with the 19 month old.
Look, the mom has a newborn. Her hormones are all over the place. Anything can upset a new mother. So honor her wishes on this. She doesn't want someone's saliva going into her toddler's mouth.
Now, about the monitor. Did you know that where you were sitting there was a monitor watching? If you didn't, that would be quite a shock. Now you know that when you come to her house, you might be monitored. Act accordingly.
When the baby is older and your friend can go out more, especially in warmer weather, meet her other places instead of going to her home. If she asks why, tell her it kind of creeps you out that you are on a monitor. If she gets upset, it tells you a lot about your friend...
Updated
What you should do is not share a spoon with the 19 month old.
Look, the mom has a newborn. Her hormones are all over the place. Anything can upset a new mother. So honor her wishes on this. She doesn't want someone's saliva going into her toddler's mouth.
Now, about the monitor. Did you know that where you were sitting there was a monitor watching? If you didn't, that would be quite a shock. Now you know that when you come to her house, you might be monitored. Act accordingly.
When the baby is older and your friend can go out more, especially in warmer weather, meet her other places instead of going to her home. If she asks why, tell her it kind of creeps you out that you are on a monitor. If she gets upset, it tells you a lot about your friend...