Non-aligned x-axes when plotting two series on the same axes
I have the following `DataFrame` that I want to create a boxplot for:

```
estimates.head()

Out[162]:
            0   1   2   3   4   5   6   7   8   9   10  11  12  13  14  15  \
DATE
2009-04-28   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0
2009-04-29   6   6   6   6   6   6   6   6   6   6   6   6   6   6   6   6
2009-04-30  10  10  10  10  10   9   9   9   9   9   9   9   9   9   9   9
2009-05-13   9   9   9   9   9   9   9   9   9   9   9   9   9   9   9   9
2009-05-14  11  11  11  11  11  11  11  11  11  11  11  11  11  11  11  11

            16  17  18  19  20  21  22  23  24  25  26  27  28  29
DATE
2009-04-28   0   0   0   0   0   0   0   0   0   0   0   0   0   0 ...
2009-04-29   6   6   6   6   6   6   6   6   6   6   6   6   6   6 ...
2009-04-30   9   9   9   9   9   9   9   9   9   9   9   9   9   9 ...
2009-05-13   9   9   9   9   9   9   9   9   9   9   9   9   9   9 ...
2009-05-14  11  11  11  11  11  11  11  11  11  11  12  12  12  12 ...
```

along with a `Series` that I want to plot on the same axes:

```
counts.head()

Out[165]:
DATE
2009-04-28    0
2009-04-29    2
2009-04-30    4
2009-05-13    2
2009-05-14    5
Name: OBS1_NMANATEES, dtype: float64
```

They are both the same length, and have the same index (in fact, to ensure the latter, I assigned the index `estimates` to `counts`). However, when I plot them on the same set of axes, the plot for the `counts` is off by one on the x-axis:

```
fig, axes = plt.subplots(figsize=(18,6))
estimates.T.boxplot(ax=axes, grid=False, rot=90)
axes.plot(counts)
plt.tight_layout()
plt.xlabel('Survey')
plt.ylabel('Population estimate')
```

![](http://d.pr/i/pHI8+)

Notice in the plot the line graph does not begin with zero at 2009-04-28 as is clearly shown in the data, and you can see the entire line is shifted. This looks like an alignment error, no?
