If K and Mg are available in the soil in somewhat near the right ratio there is rarely a problem. In my area it is also often a problem for dairies. The reason for this is that they feed lots and lots of imported alfalfa which has been well fertilized with K. So they are bringing on lots of K to the farm. Not very much of this leaves in the milk so the rest goes out in the manure which gets spread on their land. K doesn't leach off or leave in any other way so it builds up over time. I have seen soil tests from dairies with up to 2,000 ppm of K. This leads to the grass luxury consuming the K. Which leads to health problems in the cattle (grass tetany, milk fever, retained placenta, etc).
This doesn't seem to be nearly as big a problem with beef cattle. I think this is because we aren't importing tons and tons of high quality alfalfa and the cows aren't pushed for production like they are at a dairy.
Dave