Just a couple of points Vinayak:
How far to destination when you climbed? Less than 250nm and it's usually not worth it.
What did your OFP/CFP say about it? It usually knows best.
Did you insert all the winds, temps, trop etc either manually or via Acars in order to make predictions accurate?
What was econ Mach at 330 and 390 - M.78?
Please don't feel the need to reply, but the answer might be in one of the above points.
cheers
mcdhu