When there are literally 100's of pics added EACH day, it is impossible to make sure each one gets commented on. If you see one that isn't - you can go ahead and do it. There are no hard rules about having to make a comment if you link it as a favorite - I personally take it as a compliment that folks save mine, whether it is commented on or not. I know for my computer that I am usually on, it takes FOREVER for it to load each time, and that may be a reason for others also.
Just smile and think how great it is that folks love your cake enough to save it to their favorites!
I agree that it is an honor to have my photos viewed and just to be allowed to be a part of this amazing community. And I am just thankful for all the busy people that take the time to help and to answer questions. Where would we be without CC???