ReflectionException thrown on composer update for a file that exists

To make this more interesting, things work just fine if I run composer dump-autoload -o but I am curious why would this throw an error when I run composer update in the first place? I need to get to the bottom of this. A quick fix doesn't make me happy internally.

aligajani at Alis-MBP in ~/Projects/saveeo on master ✗                                                                                    [faaba41c]  4:53
> composer update
> php artisan clear-compiled
Loading composer repositories with package information
Updating dependencies (including require-dev)
Nothing to install or update
Package guzzle/guzzle is abandoned, you should avoid using it. Use guzzlehttp/guzzle instead.
Generating autoload files
> php artisan optimize

                                                                  
  [ReflectionException]                                           
  Class Saveeo\Board\Observers\BoardEventListener does not exist  

BoardEventListener.php (placed in Saveeo/Board/Observers)

<?php

namespace Saveeo\Board\Observers;

use Saveeo\Services\HashIds\Contracts\HashIds as HashIdService;

class BoardEventListener {

    private $hashIdService;

    public function __construct(HashIdService $hashIdService)
    {
        $this->hashIdService = $hashIdService;
    }

    public function whenBoardIsCreated($event)
    {
        $this->hashIdService->syncHashIdValueOnModelChanges($event, 'board');
    }

    public function whenBoardIsUpdated($event)
    {
        $this->hashIdService->syncHashIdValueOnModelChanges($event, 'board');
    }

    public function subscribe($events)
    {
        $events->listen(
            'Saveeo\Board\Observers\Events\BoardHasBeenCreated',
            'Saveeo\Board\Observers\BoardEventListener@whenBoardIsCreated'
        );

        $events->listen(
            'Saveeo\Board\Observers\Events\BoardHasBeenUpdated',
            'Saveeo\Board\Observers\BoardEventListener@whenBoardIsUpdated'
        );

    }

}

EventServiceProvider.php (placed in Saveeo/Providers)

<?php

namespace Saveeo\Providers;

use Illuminate\Contracts\Events\Dispatcher as DispatcherContract;
use Illuminate\Foundation\Support\Providers\EventServiceProvider as ServiceProvider;

class EventServiceProvider extends ServiceProvider
{
    /**
     * The event listener mappings for the application.
     *
     * @var array
     */
    protected $listen = [
        //
    ];

    /**
     * The subscriber classes to register.
     *
     * @var array
     */
    protected $subscribe = [
        'Saveeo\Board\Observers\BoardEventListener',
    ];

    /**
     * Register any other events for your application.
     *
     * @param  \Illuminate\Contracts\Events\Dispatcher  $events
     * @return void
     */
    public function boot(DispatcherContract $events) {
        parent::boot($events);

        //
    }
}