Very confused

About five days ago now I brought home two amazing girl rats from petsmart. These are my first rats I've ever had. We have Arya the brown hooded fancy rat and Toast the champagne husky dumbo rat. Arya is my boyfriend's rat and Toast is mine. They live in the same cage together. I've been doing trust training since day two. Arya caught on incredibly quick while Toast was considerable harder to win over. But by day four (yesterday) they would both be running up to the cage door when I approached and would gladly come out to play. They would run into my hoodie sleeve and explore the inside of my hoodie and would gladly groom themselves on me and take treats from my hands while being on me. Even Toast was doing this but not quite as much, she was far more interested in what was on my dresser sometimes. Unfortunately I'd have to scoop her up before she got too far because I'm worried she will fall off the back (she climbed on to my laptop and I figured she wouldn't fall but she did, I had my hands near the whole time so I quickly caught her without too much of a fall though it scared the heck out of her) of the dresser or get on to my boyfriend's layout which has all kinds of stuff that would not be good for them if they chewed on. After awhile they both got a bit used to my hands and me scooping them up. But while they eagerly greeted me yesterday, this morning when I approached the cage Arya jumped up to greet me but was unsure about climbing on my arm or in my sleeve, even when I tried to tempt her with a treat. The treat didn't seem worth it to her. While yesterday she'd climb on me no issue and gobble down the treats I gave her. I didn't do anything unusual, nor should I smell any different.
Though I know for sure the progress I've made in only four days is probably pretty awesome considering they are from pet smart.
Does anyone happen to know why this is?