In all honesty, I wouldn't consider getting a pet from Petco as an "adoption".
I believe that all animals deserve a wonderful forever home. But just like with the horrid puppy mills, most of the chain petstores get their rats from "mills" too. These regularly breed unhealthy rats, in horrible conditions. Buying a pet from petco just contributes to their horrible practices.
There are some very serious and deadly viruses that affect rats. This is why a 2-3 week quarantine is an absolute must before introducing new ratties into your home. It's much safer to go through a reputable rescue that places their ratties into QT homes before adoption.
Just my two cents.
With all that said, I hope your new rattie is healthy and she has a wonderful life with you.
They all deserve only the best.