Maybe she just feels insecure about it... has she had a kid in the intervening time?
Women tend to work like that... like somehow now her pussy isn't 'beautiful' enough... like it isn't as 'beautiful' as it was 13 years ago so you might not think like it any more and go like 'ewwww' when you go down there....
strange people... women...
Maybe you need to compliment her more on how lovely it feels and how much you love it and how you think it is one of the most beautiful things in the entire universe and stuff like that....
Ease her mind and let her know that you love every part of her and that part in particulair.