Connolly was dismissed just 15 minutes after coming on against Monaghan in Clones and lasted only 30 minutes of the Allianz League final defeat to Kerry at Croke Park.
He pulled back Peter Crowley and hauled him to the ground during an off-the-ball incident that Connolly acknowledged was down to “frustration on my part”.
The upshot of successive black cards is that Dublin’s talented playmaker will be banned for one-match if he receives another such sanction in the championship.
That threat could linger throughout the championship and, if he’s black carded later in the summer, he would miss a potentially season-defining game.
“To be honest, someone said that to me only the other day. I didn’t actually realise it. I’m obviously conscious of it now,” admitted Connolly
He also picked up a black card while playing for St Vincent’s against Carlow’s Palatine in the AIB Leinster club championship last November.
Also, his list of red and yellow-card sanctions in high-profile club and county games over the years doesn’t make for pleasant reading, but the four-time All-Ireland medal winner insisted he’s not a cynical player.
“No, I mean look, the first black card I ever got [for Dublin] was against Monaghan,” said the 29-year-old.
“I would hope no-one would see me as a cynical player. That’s not part of my game. Going forward and attacking is a big part of what I bring to the Dublin team.
“I looked back at the tape of the black card against Monaghan. It could be construed either way. The referee made that snap call and that’s his decision at the end of the day, so, I just have to suck it up.
"Against Kerry, it was frustration on my part rather than anything else, really. You look at them, you learn and you move on. That’s my thinking behind it.”
Connolly said he’s not a fan of the black card, in general.
“The black card is there and it looks like it’s there to stay for at least this season, anyway,” said the St Vincent’s man.
“It was brought in for cynical play; I don’t think it’s being used for cynical play. It should be like soccer, if it’s a clear goalscoring opportunity, it should be a red card.
"That’s how I feel. I think they have the cards to deal with this stuff, already. I think the yellow card for a pull down out the field is perfectly warranted. That’s there.
“You saw it with the U21s last weekend with arguably Dublin’s best U21 player of the last five or six years, Con O’Callaghan, who plays six minutes of an All-Ireland semi-final. Is that a cynical foul? No.
"By the letter of the law, is it a black card? Yes. So, you’ve got to tailor your game, but I don’t think it’s right. I just don’t think it’s a part of the game that we need.”
It was hoped that the rule would help forwards and attacking play, generally, by cutting down on cynical fouling by defenders.
“If you look at the black cards, the bulk of them are coming at the other end of the field,” argued Connolly.
“Which is not what the black card was brought in for. Okay, Con picked up a guy, I did it out here in Croke Park a couple of weeks ago, as well, I dragged a guy to the ground. Is that a cynical foul? Was it? I don’t think so.
"Was it a yellow card offence? Yeah, okay, fair enough, but miss the whole game?”
It was a frustrating spring for Connolly, who lost an AIB All-Ireland club semi-final with Vincent’s and then managed just over 70 minutes of action in total with Dublin.
A holiday after the league final turned into a nightmare too when he arrived at a hotel in Portugal and spied some familiar faces.
Asked if it was hard to see Kerry lifting the league trophy, Connolly said: “No, but it was hard to see some of them down in Vilamoura in the same hotel as me! Fionn Fitzgerald, his girlfriend, Darran O’Sullivan, his girlfriend.
"We rocked in on a Wednesday morning with the golf clubs and who’s sitting there only the two Kerry boys. I said hello, of course. Ah, they’re nice guys.”
Diarmuid Connolly was speaking at the launch of the Beko Club Bua award scheme, a new club accreditation and check system coordinated by Leinster GAA for clubs in the province.