I have always thought that refusal to eat would involve the snake not even acting interested in the prey.

This week my BP, always a good feeder, came out eagerly to eat, got right up to the rat (f/t), flicked it with his tongue, and then proceeded to back up into his hide.
He's come out a couple of times and done the same thing again.

How should I interpret this?
The f/t rat is part of a batch he has been scarfing down for a couple of months with no problems. Is there something wrong with the way the rat smells, or is this what refusal to feed for other reasons looks like?

This is my first refusal, so educate me please
his temps and humidity are in spec, and there have been no changes in housing or routine in months.