Logical indexing for a financial time series

I can't be asking much.. I want to be able to logically index a time series function and I cannot seem to do it without extracting the data matrix.

Here's an example:

data  = (1:10)';
dates = busdays(today-11, today);

Generate time series

ts = fints(dates, data);

I want to find the date where my ts value is 4

find(ts == 4)

But I get:

ans =

       []

Now if I do the following, I get the result I am after.

datestr(ts.dates(fts2mat(ts) == 4))

ans =

11-Oct-2012

Is there a way of logically indexing a financial time series object directly?