I once tied my dog to a sign and went into a book shop to pick up an order. While I was in there less than 5 minutes, it started to very lightly sprinkle. A 'good samaritan' untied the dog and retied him to tin A frame sign under the verandah. When he saw me he jumped forward dropped the sign over, spooked and ran lead attached as it slipped off as soon as the sign fell. I never saw him again. That was 30 years ago and I can still recall how I felt.
I will never leave a dog outside the shop again. I am very glad you were lucky.