That came in the form of a penalty try in the closing stages with Leinster wing Rob Kearney slotting a drop goal in a less than impressive contest between the two Irish provinces.
And, with last year's Heineken Cup runners-up Northampton next on the agenda as the focus switches to Europe, O'Connell has called for a reaction from Munster.
"I was unhappy with the way we finished it was very disappointing," said skipper O'Connell. "Obviously with the amount of penalties we gave away we will have to look at our discipline.
"We just conceded momentum. It's very hard when you give away penalties like that and that was frustrating for us."