guava: LoadingCache.getIfPresent(key) returns null after LoadingCache.getUnchecked(key) returned non null value

I am using the LoadingCache in a highly concurrent system and I observed some behavior that I am not sure is intended (to me it looks like a bug 😃 ). I wrote the following sample code to illustrate the problem :

public static void main(String[] args) {
        final LoadingCache<String, Object> cache = 
            CacheBuilder.newBuilder()
                                 .expireAfterAccess(65, TimeUnit.MINUTES)
                                 .build(new CacheLoader<String, Object>(){

                                                    @Override
                                                     public Object load(String arg0) throws Exception {
                                                                Object obj = new Object();
                                                                    System.out.println("creating object: " + obj);
                                                                    return obj;
                                                     }
                                  });


        int threadCount = 600;
        final String key = "hello/world";
        Runnable task = new Runnable() {

            @Override
            public void run() {
                try {
                    Object valueFromUnchecked = cache.getUnchecked(key);
                    if (valueFromUnchecked == null) {
                        System.out.println(Thread.currentThread().getName() + " valueFromUnchecked is null!!!");
                    }

                    Object value = cache.getIfPresent(key);
                    if (value == null) {
                        System.out.println(Thread.currentThread().getName() + " value is null!!!");
                    }

                    if (value != valueFromUnchecked) {
                        System.out.println(String.format(Thread.currentThread().getName() + "valueFromUnchecked:%s, value:%s", valueFromUnchecked, value));
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        };

        for (int i = 0; i < threadCount; i++) {
            Thread t = new Thread(task);
            t.setName("thread-" + i);
            t.start();
        }

Sometimes thing are fine, I don’t get the output of “<thread name> value is null!!!” lines and some times I do. I never get the output of “valueFromUnchecked from getUnchecked is null!!!”

My understanding of from LoadingCache java doc, is that if getUnchecked() does not return null then getIfPresent() shouldn’t return null as well; given that the cache has not expired yet.