If the OP had been in sight, I would agree with you. The fact that DD was there, apparently by herself, is what sends this into creepy territory for me.But... I just explained that his assumption was probably that the OP was still in the house fetching money, while the daughter flagged him down.
Or that the kid might change her mind, and go into the house to get money.
in fact, that argues that he was probably not trying anything creepy. He *knew* that a grownup would have to be present for the transaction, bcs the grownup has the money.
But the *kid* often has the "buying decision"--or at least *starts* the buying decision. The kid says, "hey, Mom/Dad, can I have ice cream?"
And if the was looking at the street (and the truck, which she surely could hear), maybe he thinks she's teetering on the verge (ice cream? Maybe?), and he thinks that if he calls out to her, she'll decide to go ask the parent who is surely indoors.