Sorry, the 'not' got lost.
This shouldn't be a problem.
But of course, this is a possible but not very likely source of bugs. If you look at the documentation of SimpleDateFormat, you'll see that there are two methods to apply a new pattern.
So it's possible that one thread changes the pattern while another uses the old pattern. But that looks very unlikely given the name of the variable. (I assume the CSV pattern doesn't change during runtime.)
If the final variable is encapsulated in a CSVWriter class or something the possibility is even smaller.