I understand that, while not ideal, a small amount of fuel entering the engines is nothing to worry about. Only a large amount, resulting from an uncontrolled spillage, would be enough to worry about. That said, engines aren't my bit so don't quote me on that.
However, in relation to the A-10, there is a known issue with spillage after AAR. The area that is covered by the fuel includes the intake for the pilot's oxygen system (I'm not aware exactly which type of system this is). This means that a spillage after AAR can lead to fuel fumes in the oxygen system, which can, in turn, lead to hypoxia.
This theory was considered for a long time before finally being rejected as being a primary cause of an A-10 crash a few years back. Essentially, the pilot lazily flew around for quite a while before parking his plane in a hill. Both pilot and plane were written off. The detailed description of his flying style reminded many of the actions of a hypoxic, but (if I remember correctly), the BOI finally concluded that it was a deliberate act.
I'm afraid I'm a bit hazy and I'm sure that some of you are far more informed than I, so please feel free to correct or add details.
The definition of a 'Pessimist': an Optimist with experience...