Bias current and offset voltage, op-amp 741 DC imperfections
In short to answer your question, you can get an amp with an offset voltage near 0V (and it also depends on how you measure the offset). Its possible with almost any amp. Why does this happen, it really depends on the op amp and how it was designed and manufactured. This is a histogram of the offset voltage for a different amplifier OPA1622, but most of them are similar.

The histogram follows a normal distribution and it would be possible in some circuits to have the total offset be zero (because there are other elements like bias current that might give it a positive error and the offset voltage could be negative). 

The bad news is, this will never hold over temperature, the offset voltage will drift with temperature. That means if your application requires accuracy, you calibrate the analog signal chain over temperature (or minimize the effects of offset so they don't matter for the application).