Two Caveats first.....
Seems like there is NO clear definition everyone follows regarding size of prey so what is a small mouse to one could be a large one to another.
No two snakes are the same, I do have a BRB that I'd be quite happy if she'd take a large pinky and a hopper IMO would be too large but then again, she is a tiny thing at only 13 grams, was one of a pair of twins.
Does not sound like you over fed UNLESS you keep up this type of feeding. Give it a day or two and see how she looks, like Jeff said you are right at the time she should reduce the meal. If she still looks overly large in a dya or so you can always skip her next meal with no harm at all to your baby. She could go for months in the wild with no food at all without any long term affects. Other than not growing and still being so small and a more likely meal for another predator.
More important is the long term feeding regimen. Altering the size of prey up and down on a weekly basis is no big deal as long as the average size of prey is correct. Rule of thumb is food should be same diameter as the widest part of snake (empty). Of course each snake can be different and also each snake can change!! My Amber only wanted small meals and grew very slowly. only half the size of her siblings. Now at two years old she is going throuhg a growth spurt and is eating much larger prey.
Just pay attention to how your individual snake is doing. If she starts looking stretched out and skin always showing between the scales, back off on food a bit. If eshe is looking skinny and wants more, give it to her!!!
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Thanks,
Dave Colling

www.rainbows-r-us-reptiles.com
0.1 Wife (WC and still very fiesty)
0.2 kids (CBB, a big part of our selective breeding program)
LOL, to many snakes to list, last count:
24.36 BRB
19.19 BCI
And those are only the breeders 
lots.lots.lots feeder mice and rats 

