Aberdeen manager Craig Brown felt the first of Ryan Jack's two bookings in the defeat by Celtic was "harsh".
Jack was booked after celebrating the Dons leveller and later picked up a second caution to be sent off.
Ki Sung-Yueng scored the opener in Glasgow and Charlie Mulgrew fired Celtic's winner.
"It's not a bookable offence to leave the field of play I understand. He did no harm to anyone," Brown told BBC Scotland's Sportscene programme.
"He quickly turned, he went off towards the fans to celebrate. That's an instinctive thing, you go to your own fans, and he turned back in again.
"He hadn't to be shepherded by any steward, the stewards were there certainly, but they hadn't to push him back on. The referee didn't come and tell him to get back on and then he was cautioned."
Brown accepted that Jack's second booking, for a late tackle on Gary Hooper, was merited.
"The (first) booking cost us an ordering off because he had a second yellow, which he deserved but I think the first one was very harsh to book him when it's not an offence to leave the field," added Brown.
"He (Jack) is not a malicious guy. I've got to credit Hooper with some good quick feet. It was a rash challenge.
"Admittedly it was an inexperienced challenge but not a malicious one and I would agree that that deserved a yellow card but I don't think the first one did."