Bryan,
As Bobby Jones stated, "there's golf and then there's tournament golf" and boy was he right about that.
Tournament golf, probably more so medal play, brings a unique pressure to the play of the game.
Obviously, that pressure manifested itself in your putting.
It's not the greens, it's your mind.
I truly believe that that's what seperates the great ones from the good ones from the fair ones, "the mind" The ability to perform under pressure.
I"ll bet if we played the next day, just for the fun of it, your putting would be fine, but, with the pressure of the event, your mind, not your putter betrayed you.
I had the same thing happen to me qualifying for the USGA Senior Am, I had four 3 putts, sometimes missing 1.5 footers and I missed two 4 footers for up and downs and missed by one stroke. My putting stroke was nothing more than an extension of my mind set, which on that particular day wasn't good when it came to putting.
Pressure and your mind, not green complexes and your putting stroke are the problem.
Heresy of heresies, I'm thinking about trying the long putter.
I still putt well from a distance as my distance control remains excellent. I just can't see the line, I can't line up on my intended line and I'm more fearful of a three footer than a ten footer.
Just wait until you get to 70, it won't get better unless you conquer your mind