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Calculating Daily Returns with Quantmod for R

First, I am still quite the novice when it comes to R in general.

I am finding some odd results with quantmod's functions for daily returns.

Start with the following code:

Then I perform the following:
> testRet[2]
                daily weekly monthly quarterly
2007-01-04 0.01896392    NA      NA        NA

> QQQ$QQQ.Adjusted[2]
2007-01-04        42.97

> QQQ$QQQ.Adjusted[1]
2007-01-03        42.17
> (42.97-42.17)/42.17
[1] 0.01897083

Can somebody help me with this one? Is it a rounding issue?