You've got low temps (as far as the hydraulic fluid is concerned), and if you're just grading (****-u-ming just picking up and dropping a rear implement) you probably aren't exercising the system all that much. Betcha you've got air in the system that will take time to work out. A previous poster mentioned higher temperatures to really work the air out and I'm guessing it was more like 80 or 90 degrees than 60.
Don't know about valves for the front hydraulics - mine doesn't have them. If you have the back valve all the way open (and I'd recommend that you do so until you work the kinks out), it should take care of itself in time, I believe...