False ValueError in `pandas.to_datetime`?
While trying to convert a Series of string dates to datetime objects using `pandas.to_datetime`, I get a ValueError indicating a bogus date:

```
In [11]: hospitalized['birth_date'] = pd.to_datetime(hospitalized.child_birth_date, errors='raise', format='%Y-%m-%d')
    newborns['birth_date'] = pd.to_datetime(newborns.birth_date_newborn, errors='raise')

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-11-b2cd6c80de7e> in <module>()
----> 1 hospitalized['birth_date'] = pd.to_datetime(hospitalized.child_birth_date, errors='raise', format='%Y-%m-%d')
      2 newborns['birth_date'] = pd.to_datetime(newborns.birth_date_newborn, errors='raise')

/Library/Python/2.7/site-packages/pandas-0.11.0rc1_20130415-py2.7-macosx-10.8-intel.egg/pandas/tseries/tools.pyc in to_datetime(arg, errors, dayfirst, utc, box, format)
    102         values = arg.values
    103         if not com.is_datetime64_dtype(values):
--> 104             values = _convert_f(values)
    105         return Series(values, index=arg.index, name=arg.name)
    106     elif isinstance(arg, (np.ndarray, list)):

/Library/Python/2.7/site-packages/pandas-0.11.0rc1_20130415-py2.7-macosx-10.8-intel.egg/pandas/tseries/tools.pyc in _convert_f(arg)
     93                 return DatetimeIndex._simple_new(values, None, tz=tz)
     94             except (ValueError, TypeError):
---> 95                 raise e
     96 
     97     if arg is None:

ValueError: day is out of range for month
```

However, if I iterate through the elements of the Series to see where the bad date is, I do not get the error:

```
In [10]: hosp_birth_new = np.empty(len(hospitalized.child_birth_date), dtype=object)
        for i,b in enumerate(hospitalized.child_birth_date):
            try:
                hosp_birth_new[i] = pd.to_datetime(b)
            except ValueError:
                print b
        hosp_birth_new
Out[10]: array([datetime.datetime(2010, 2, 2, 0, 0),
       datetime.datetime(2010, 1, 29, 0, 0),
       datetime.datetime(2009, 3, 28, 0, 0), ...,
       datetime.datetime(2012, 9, 19, 0, 0),
       datetime.datetime(2013, 2, 28, 0, 0),
       datetime.datetime(2012, 7, 2, 0, 0)], dtype=object)
```

Running pandas-0.11.0rc1_20130415 on Python 2.7.2 (OS X 10.8.3).
