Alot of my snakes have been eating f/t thawed for years, and I would say a good third of them are what I call "lazy eaters," like your little burm. Some of them just bite it, pull it down, and start eating it - no coiling done, EVER. Others don't even come get it, I just place it in their bin and they'll take it, again, no striking or coiling. Lazy snakes I say; spoiled by their easy, struggle-free food items, LoL.
I thaw out all mine in zip locks backs floating in Warm/Hot water. I just plug up the sink and set them in there, since I'm thawing 80+ rodents at a time.
Also a good idea would be to have a hair dryer on hand. Frank will use my hair drier a lot when he's feeding the critters, and it seems to always help and does the trick!