I have seen this a fair amount too.
To add to your explanation as to what you are seeing:
It seems that if i get hits, but cause only superficial damage (no parts lost or major damage,) I will see hit sprites.
However if i get a hit which causes major structural damage (usually a wing falling off) or a pilot shot that causes an explosion, then i will see nothing at all in way of hit sprites.
Seems to be pretty consistant that way.
