2004 Jeep Liberty Steering sticks

My 2004 Jeep Liberty (85,000 miles) recently developed sticky steering. In the morning, or after sitting for some hours all day like at work, I can barely turn the steering wheel. Suddenly, it will break loose and work fine from then on, although it will squeak upon turning for a few minutes. This happened only intermittently at first, but has become much worse recently. Is this a dangerous driving problem? I do drive to work down the German Autobahn at high speeds (80-100 mph). The power steering pump is only two years old, and has plenty of fluid, although I do not think that has anything to do with this.

Thank you!