No worries, it happens
I have one snake that is driving me crazy. My Pastel Lesser. I swear she has some issues...sigh.
She ALWAYS grabs it right by the head, constricts and then proceeds to look it over and over for a long time. After which she tries to swallow bum first. Or sideways. Or grabs a FOOT first. Sigh.
Yes, the food is frozen thawed but warmed appropriately. The food size is right. She is the only one that does this and I can't stand to watch her eat, it drives me crazy. She is in a tub, but I can still peek in and see her shenanigans.
I learned, the best way is to walk away and not watch. She always manages to eat it somehow.