Is it OK for a stranger to touch your kids face when you are around?

So is it OK to allow someone to touch your child's face when  you are around. Today I felt a sense of discomfort when I woke from my sleep cause the back of my mind I was thinking about the incident that happened last evening.  Nathan and I were waiting at the store whilst papa paid for the  grocery. The old man in his 60s who was selling sweets approached us and casually asked if Nathan can transform his scooter into a robot. I responded on his behalf. But the old man touched his cheeks and said this boy is so shy. I was irritated, yet I held my composure and got Nathan to move away from the stall. No matter how old the other party is, I don't feel good when they attempt to carress the face of your kids. I told myself this will not happen a second time.