One of my "must read" newsletters is written by John Mauldin and it's called – appropriately – John Mauldin's Weekly E-Letter. I get it each week in my inbox; I suggest you do the same.

I will caution you, however, that it may scare the pants off of you! Lately (the last few years), his commentary has been rather harsh. But, hey, look at the economy!

All that said, I encourage you to read this week's letter. One astonishing number came out this week: GDP growth of 5.7 percent! Yay, roll out the marching band and dancing monkeys, the recession is over!

But wait.

The Statistical Recovery Has Arrived

Before we get into the main discussion point, let me briefly comment on today's GDP numbers, which came in at an amazingly strong 5.7% growth rate. While that is stronger than I thought it would be (I said 4-5%), there are reasons to be cautious before we sound the "all clear" bell.

First, over 60% (3.7%) of the growth came from inventory rebuilding, as opposed to just 0.7% in the third quarter. If you examine the numbers, you find that inventories had dropped below sales, so a buildup was needed. Increasing inventories add to GDP, while, counterintuitively, sales from inventory decrease GDP. Businesses are just adjusting to the New Normal level of sales. I expect further inventory build-up in the next two quarters, although not at this level, and then we level off the latter half of the year.

Did you catch that? If not for the build up of inventory, our economy grew by only 2 percent. And we know these things ALWAYS revise DOWN.

Read the rest of the letter here. I think you'll learn a lot; I always do.