Ther are occasional sightings of bears in northeast iowa, just as a moose moves through northcentral Iowa every few years. They come from Minnesota. The mountain lions have been seen throughout southern and southwestern Iowa for the last couple years and the sightings have really accelerated this year.
As far as the bears by Leon, I believe they came from southern Missouri where there is a decent bear population. The fact that it is a sow with cubs really makes you wonder how many there area. I live in very good bear country and spend a lot of time out looking for bear sign and hunting them, in addition to the hundreds of hours glassing field edges, clearing and logged areas for deer, plus trapping in the forest. You just don't SEE bears. They are super wary and can slip away like a wisp of smoke. I have seen a total of three in the last two years. When you start seeing bears now and then, you've got more than just what you are seeing.