Depending on how it was worded, it may be correct. Foods like apples, grapefruits, oats, other whole grains, etc...slow digestion. So if it was in reference to a post-workout protein shake, which you would want to absporb quickly, then drinking it immediately after a meal containing those foods could techinically decrease absorption, or at the very least delay it.
Also, the pectin in apples increase and slow glucose release and absorption. Again, defeating the purpose of post workout nutrition.