I know the question is asked in the article but I can't find a logic answer : why were they arguing ? It's not like the lead was cut down or they were themselves down by a big margin.

Let conjure to guess, just for fun.
I'm guessing Smart was yelling at Brown for stupid foul at the end of the half, after he dove on the floor trying to make the steal. Then Crowder yelled at Smart to leave him alone.
Then IT told everyone on the team " I will F*** you all up"!
Anyone else want to guess?

I'd be more worried if things like this didn't happen.

Despite what fans concoct in their own minds, I've never been associated with a successful team where there weren't conflicts - personality and the like. If there aren't, your team may be too soft or too apathetic to win.

And if you have good leaders, it's no big deal.

As long as it wasn't about some woman, they should be ok.