First off a baby that small shouldn't fast. First a pinky mouse or rat is way too small for her. When I got Dottie, she was about 90g and I was feeding her fuzzy rats or hopper mice. That could possibly be why she is not eating, its just too small. Second you said heat lamp side and UTH side, those should be on the same side and it should be 88-90F on the hot side. Cool side can dip down to high 70s but I personally try to keep cool side ambient around 80F. Third thing is I generally avoid handling my new snakes until they have eaten 3-4 times in a row. Once they are comfortable enough to eat regularly, then I start working on the friendship.
As for being concerned, is she looking skinny? Has she gone poop? Pee? Drinking water? 5 gram loss can come from any of that. But as for a little 106g baby not eating a month, I would definitely work on what I listed and then possibly get ready to assist feed if nothing for another 2-4 weeks especially if she starts looking skinny.