In a game against my longtime and frequent opponent, I was playing as Chaos Daemons against Necrons, and charged a unit of Immortals lead by his Overlord (also Warlord) with my Warlord, a Greater Daemon of Tzeentch, Lord of Change. As his warlord trait, my Greater Daemon got the one where any characters he kills in a challenge will be worth an extra victory point (on a the personal tree)
Now, the battle had not been going my way, and I admit I was flustered when his exile ray randomly lucked out and obliterated my allied Chaos Lord in a unit of berzerkers, but otherwise, we had been pretty cordial (as usual).
Anyway, I of course issued a challenge with my Greater Daemon on his Overlord in hopes to either slay him or the 3 immortals left over. When I do that, my opponent erupts instantly into saying that it's a cheap rule which shouldn't exist, because it turns a game of units into a game of characters. Secondly, he suggested I was being a bit of a jerk because I had quote "no chance of winning the game if I didnt do this" and further that he had "no chance of beating me one-on-one with either the overlord or the immortals, and that forcing him to do so was, not kind of me. I disagreed with all of his suggestsions.
We got into a heated argument in which I raised my voice a few times, because I had felt like it was unfair to say my one chance at glory was cheap, when I've had to fight tooth and claw to stay in this game as Daemons to begin with...
Anyway, all this aside... should I feel bad for issuing a challenge? Should I save it for the tourney field and not against my usual opponent?