I am no expert, but you always are going to have some subtle differences when you buy a mix paint. It isn't the paint stores fault in my opinion. You would have been better off buying another 1.2 gallon and mixing (boxing as it's called) it all, then re-painting the whole thing.
It's the same for house paint, it just doesn't suck so bad if one side of the house isn't exactly the same as the other (and a lot less noticeable).
The good news is that you know how much paint it will take to paint it again.
JJ
69 Fastback 302 2v 3sp. trans.
http://albums.photopoint.com/j/View?u=1605599&a=12251632&p=44630868&Sequence=7&res=high.jpg
It's the same for house paint, it just doesn't suck so bad if one side of the house isn't exactly the same as the other (and a lot less noticeable).
The good news is that you know how much paint it will take to paint it again.
JJ
69 Fastback 302 2v 3sp. trans.
http://albums.photopoint.com/j/View?u=1605599&a=12251632&p=44630868&Sequence=7&res=high.jpg