They've acknowledged they are here, but only in the last 10 year or so. They kind of had their hand forced when one was treed on the outskirts of Tulsa and it was all over the news. They do however state that they are most likely just "passing through".
If they are male, that is more than likely true. They get pushed out of the Black Hills and Rockies by the dominate male, they just keep traveling following food and looking for love.
We have some in Iowa now, only been one female killed the rest have been male. More than likely followed the Missouri River here. Historically they were found just about everywhere in the US, so I don't find it all that strange.