Astronomers scared of ever-brightening star

"Julius Caesar might have said he was as constant as the northern star, but it wasn't much of a boast. Over the past two millennia, the star Polaris has brightened by 250 per cent, astronomers announced today."

This article has a worrying lack of citations and I'm inclined to doubt the overall veracity of the claim. But, man, I love the idea of stars getting brighter for no apparent reason.