Just that really? Saw a man holding his baby walking round the tube and letting the baby grab the rails etc and then just watching the child lick their hands after??
As a lifelong tube commuter I have seen people (blokes) scratching their arses or picking their noses and then casually grabbing the handrails.... to think a baby will be licking their hands after touching it horrifies me!
Would it be reasonable to have said something to the man?