Hydraulic fracturing for stimulation of oil and natural gas wells was first used in the United States in 1947. It was first used commercially by Halliburton in 1949, and because of its success in increasing production from oil wells was quickly adopted, and is now used worldwide in tens of thousands of oil and natural gas wells annually. The first industrial use of hydraulic fracturing was as early as 1903, according to T.L. Watson. Before that date, hydraulic fracturing was used at Mt. Airy Quarry, near Mt Airy, North Carolina where it was (and still is) used to separate granite blocks from bedrock.
OK, so it's been around awhile..
With the explosive growth of natural gas wells in the US, researcher Valerie Brown predicted in 2007 that "public exposure to the many chemicals involved in energy development is expected to increase over the next few years, with uncertain consequences." As development of natural gas wells in the U.S. since the year 2000 has increased, so too have claims by private well owners of water contamination. This has prompted EPA and others to re-visit the topic.
and it's getting more prevalent...
I don't think anybody is saying that it's "suddenly" causing problems. It seems like the concern is the growth. As much as I dislike using a car analogy, I think if we hadn't have chosen automobiles as our primary form of transportation, we wouldn't have emission standards and the like, because what makes it an issue is quantity. We'd be fools to not question or investigate this, especially since fracking is questioned international. It's being investigated in many countries, and it's already banned/stopped in others. What if they're right?