That's a pretty good result given your knee and leg issues.  An yes the weather was really nice on Saturday.

For me on hills, I sometimes treat them this way.  I don't start to get tired until perhaps a third of the way up when my breathing starts to speed up and my stride is shorter.  I then think that it did not take me too long to get this far, and I only have about half left, so the hill is almost over.  I also know that at the crest there will be a downhill and I can rest while opening up my stride and catch back any lost time.  Its all a matter of perspective.  Sort of like a nice dinner - do you slog through the brussel sprouts first, saving the scallop for last; or eat the best part first and then have to force yourself to eat the vegetables.

Hills will drain your energy yes.... but so will running 15 sec faster on a mile than you should.  You still had a mile to go after the hills so just slog through them (think brussel sprouts) and know at the end you can savor the main course when you are done.