this is not at all strange to me, especially of you have a kid WITH you and you are clearly looking for a lost pet. i think that's different than intentionally going to a place to specifically talk to children. i wouldn't have chased you away with a broomstick! kids are outside, they notice animals, they can definitely be a big help. but if i saw someone hanging around the school waiting for kids to get out and walking up to them- hackles up. glad you found your dog!!!