Actually, no.  The line is relying on the order of operations rules to actually truncate the milliseconds off the timestamp.  So if you really want parens you need to write:

  lastModified = (sender.getLastModified() / 1000) * 1000

But I don't bother because that's the natural order of operations as we are all taught in grade school, and as the language has defined it to be (because of our grade school teachings).