Yeah, I typically hand him treats inside the cage or I take him out, but after he opened his mouth to my finger (my hand was inside the cage - as I said, I sometimes scratch behind his ear when he's snuggled in his little house), I just slipped the treats through the bars that night (since he kept running up to me everytime I got near the cage. It's not something I have been doing to make a habit out of, for the very reason you stated above. I only did it the one time with the dog biscuit AFTER he was already acting differently.
I think he is just feeling better and more comfortable now, and it just took me by surprise! As we speak, he is tickling the back of my neck with his whispers. I am sitting against a chair in the room, and he hopped up onto the chair and was climbing onto my shoulder. Since I have had him, I have taken him out quite often and handled him so that he gets used to it and realizes that hands aren't scary!
Haha, he's carrying a wrapper from a frozen banana I ate earlier, across the room. I don't know where he thinks he's going to stash it... Oh nevermind, he abandoned it. Now he's running back over to the chair. xD
I was just taken by surprise that night since that was the first time he had behaved that way (he was a COMPLETELY different rat, I swear!). Now I see that he is just more comfortable
All is well. He seems to be more bold now, which is fine by me, since now I don't have to keep encouraging him to come out. He just comes out on his own, and is happy to do so.
As for a name, my fiance has been calling him "Splinter" -.-; in reference to Master Splinter from TMNT... Ever since he decided to name the rat Splinter, he is more interested in him now (he's not a big rodent fan... whereas I've had small rodent pets all my life). I thought maybe Yoshi would be a cute name, but not Yoshi from Super Mario. Then again, when I adopt his companion soon, I could call them Yoshi and Splinter. But still... I don't really like calling him Splinter
He's too cute to make me think of something painful like splinters!
Seriously, though, I am considering Eli. Thoughts? I think he looks like an Eli. It's the one name I keep going back to.