To being completely obsessed with where devil fruits come from and how an 8 year old girl came upon one. Of curse 8 being near the same age as Luffy when he got his and a lot older than Chopper when he got his.
I'm not obsessed, I'm just pointing out that it's a plothole unless Oda gets around to explaining it. All I'm doing was defending my perception of it being so. This wouldn't be a forum without discussion, after all. :/
Luffy got it from an extremely powerful pirate - a yonkou - on the Grand Line and even the New World. Chopper's still doesn't make much sense, but at least he lived on the GL where DFs are more common and one might have somehow ended up on his island. Robin however, did not live in the Grand Line so one just floating there doesn't make any sense, nor did she ever meet a yonkou or a pirate for that matter, or leave her island, like Alvida did to gain hers. It would have made a lot more sense had Robin gotten her fruit in the 20 years she was traveling and running away from the WG.
I just wish Oda would have explained how Robin and Chopper got their fruits.