Holt, a late substitute, was lucky to escape punishment for a nasty challenge on Chico Flores that saw him stamp down on the defender's shin.
"For Grant there's that thin line because he wants to come on and make an impact," he said.
"Grant is a very determined player and if I look at the bookings he's picked up when he's come on, it's nothing malicious, just an over-exuberance.
"It's not frustration at coming on late, that's part and parcel of the game. Grant understands that. He's our club captain and will play a part in the rest of the season.
"It will be a difficult year for us next year and that's why we must do well in the transfer window and keep as many of our important players as possible."