No in this situation I dont think you should feel bad.

If the line was an obvious mistake and you knew that and took a shot, then it would be a different story - but in this case where the line was correct initially and they just hadnt reacted quickly enough to the injury news, then I have no sympathy for the book - if they dont want to get caught out on injury news like this then hire someone to monitor the lines better overnight.

However, at the same time, dont be surprised (or complain) if you find your account there limited or even closed entirely (depending on what book it was) but in this case the book would have no right to try to screw you by calling "bad line" on this one so should pay you up in full !