I'm sure everybody has their own method, but what I do is:

I take the mouse out and put it in a ziplock bag, and I let it sit out for a few hours to thaw out(usually about 4 hours)

Then I make sure its fully thawed, then I run hot water and I let it sit in hot water for about 30 mins, and then I re-run hot water and let it sit for about 10.

I make sure its not too hot(which it's usually warm) and then I feed. Some snakes like you to wiggle it in front of them, some of them just like you to put it there and they will get it when their ready.

What it kind of sounds like to me is your wiggling with your hand, and the snake sees its food(mouse) held by this huge hand & arm and it probably scares it away, to as where if you were using tongs, tong's don't emit any type of body signature heat. Like I said though some snakes will eat it, my anaconda I hold the mouse by the tail and wiggle for a split second and she hits it and coils it.