That nobleman must have tipped him off about the price on my head.
This nobleman is an episodic character on Once Upon a Time. A run-away Snow White approaches him to sell a piece of valuable jewelry, but realizing who she really is, he tips off the Woodcutter about the bounty price on her head.
Before the Curse
Snow White accidentally exposes herself to the nobleman. ("Heartless")
We see Snow wandering through an Enchanted Forest campsite during her early days on the run from the Queen. She approaches a nearby nobleman, working to get his attention, and when she finally has it she holds out a valuable-looking brooch and asks if she can interest him in a piece of jewelry. He takes it for inspection, commenting that the girl before him doesn't look like a peddler, and she says she's not, explaining that there was an emergency and she's been forced to sell; she adds that the brooch would make a lovely gift for his wife and the nobleman ponders this, eventually deciding to offer her three coppers. Snow is taken aback by this, as hard as she might try to mask it, for she is sure the man must realize that it is worth a hundred times that, being a family heirloom. Finding this curious, the nobleman states that he only knows one family with heirlooms this valuable, and Snow appears worried now as she fears he may be figuring out who she is. He asks for her name and she responds by telling him that three coppers will be fine - just fine. She takes the money from him and gives thanks, then running off into the woods. The nobleman is left looking highly suspicious, and eventually sends the Woodcutter after her, realizing who she really is. ("Heartless")