Experiments enhanced the validity of General Relativity, but it has not been confirmed or "proven." Just as Relativity showed the limits of Netwonian physics, so has quantum theory shown the limits of Relativity. Knowledge continually changes.
Sorry, I was being a little loose with my definitions. The point I was trying to make is that GR was a big theoretical jump in first principles, but it had direct specific and testable predictions that were shown to be accurate. Of course, GR breaks down in the realm of the very small, leading to QM.