Here is the truth...
pastels very greatly even throughout their own lines. What I mean by this is selective breeding of course. When you take an exceptional lemon pastel and you breed to a dark normal just because she is normal does not mean she is not genetically dominant in her darker color.
For instance I have an original nerd super lemon purchased directly from kevin. When bred to my butter I produced a few pastels that were more yellow than their super daddy. I held these back and bred them and created a new super female that shuns all the others even grandpa.
Now I had nothing else going on and bred a normal male to her that was incredible in color. Being high gold and yellow I was hoping to get some nice pastels and I did. Really light pastels that only turn more yellow and brighter every shed.
Through carefully selecting I have produced some incredible lemons and through some not so great crossings produced some lower quality also.
Right now the best pastel I have is a selectively bred lemon blonde male that was produced from my super male to a original matrix female. He is not a super but is one awesome pastel making my supers look bad.
Pastels are a dime a dozen. Good pastels are few and far between. Lemons tend to get brighter with age. Good luck to you. Couldn't see pics so I hope it turns out like a lemon peal for you...