how can i learn to not take things personally

i was coming back to my apartment from the shops earlier today...and approaching the entrance to my apartment block i saw a big mixed race lady with her hoodie pulled up walking her dog and with a little toddler...she shouted ' good boy, good boy' and she did this as i walked past her....and i took it personally , like she was inferring those words at me personally? i do have paranoia but i'm just a man who tries to mind my own business...and i get easily irritated by people.

anyway, how should i have handled this woman saying that today? i felt she was directing those words at me and being over familiar with me when i don't know her and she does not know me?

anyone?