CHIP was originally funded as a 10-year program. When the original funding ran out in 2007, it was extended for two years (to 2009) under George W. Bush with little incident (he had previously vetoed an expanded version but later signed the extension of the existing version).
Under President Obama, CHIP was extended (and expanded) again through 2013. The Affordable Care Act added another 2 years to CHIP, extending funding through 2015. In 2015, CHIP funding was extended again, through September 30, 2017.
The completely GOP-controlled Congress allowed CHIP funding to expire. Most state still had a few months worth of money held in reserve for the program, but some started sending out termination notices to the parents of enrollees, letting them know that they'd be kicked off the program within the next month or two.