Gulpfile not watching scss

Question

I have a simple gulpfile that loads a javascript object from a json file (to get paths based on environment), compiles my scss files, moves them to my public directory, and also moves any javascript files to the public directory.

So my assets in /app/Http/assets/js and scss are compiled and moved to /public/assets/js and css

Here is my gulpfile.js:

var gulp = require('gulp');
var gutil = require('gulp-util');
var notify = require('gulp-notify');
var sass = require('gulp-sass');
var autoprefix = require('gulp-autoprefixer');

// Load the application config
var config = require('./env.config.json');

// Where do you store your Sass files?
var sassDir = 'app/Http/Assets/scss';

// Which directory should Sass compile to?
var targetCSSDir = config.assets_path + '/css';

// Where do you store your CoffeeScript files?
var jsDir = 'app/Http/Assets/js';

// Which directory should CoffeeScript compile to?
var targetJSDir = config.assets_path + '/js';

/** Tasks **/
// Compile Sass, autoprefix CSS3, and save to target CSS directory
gulp.task('css', function () {
    return gulp.src(sassDir + '/**/*.scss')
        .pipe(sass())
        .pipe(autoprefix('last 10 version'))
        .pipe(gulp.dest(targetCSSDir))
        .pipe(notify('CSS minified'))
});

// Move Javascript
gulp.task('js', function () {
    return gulp.src(jsDir + '/**/*.js')
        .pipe(gulp.dest(targetJSDir))
});

// Keep an eye on Sass and Javascript files for changes...
gulp.task('watch', function () {
    gulp.watch(sassDir + '/**/*.scss', ['css']);
    gulp.watch(jsDir + '/**/*.js', ['js']);
});

// What tasks does running gulp trigger?
gulp.task('default', ['css', 'js', 'watch']);

This is working fine for my javascript. Also, when I run "gulp" the first time, it compiles all my scss files and moves them accordingly. However, the watch task is not working for my scss files. It DOES work for javascript files. What's really weird (to me) is that when I change my scss source to a specific file, the watch works. So,

gulp.task('css', function () {
return gulp.src(sassDir + '/**/app.scss')
    .pipe(sass())
// and the rest is the same

will watch AND compile any changes to my app.scss file, but obviously not to any other scss files.

I have re-arranged and googled all I can. I don't understand why it won't work for watching scss.

EDIT: Strangely, it seems to be notify that is breaking the css watcher. When I comment it out like so:

gulp.task('css', function () {
    return gulp.src(sassDir + '/**/*.scss')
        .pipe(sass())
        .pipe(autoprefix('last 10 version'))
        .pipe(gulp.dest(targetCSSDir))
        //.pipe(notify('CSS minified'))
});

everything works as expected.

Thanks in advance.