They knocked on though and Leinster's 16 points, all from Sexton, were enough to seal a three-point margin of victory.
"When you're on your line with one minute to go, they score a try and win, you feel like you got away with it," said Sexton.
"A draw probably would have been a fair reflection of the game really and I think they would have taken the three, they probably just felt they needed a win in terms of their league position and to get into the top four.
"You can see where they were coming from, but if they had taken the three it probably would have been a fair result."
The win put Leinster top of the Guinness PRO12 table after Connacht were beaten 18-10 by Ulster on Friday night, and Sexton was happy to bounce back after last weekend's loss to Pat Lam's side.
He added: "To do it on Saturday was a step forward and there's plenty of stuff to work on, it wasn't perfect.
"We need to improve going forward if we want to win this league, but the most important thing against Munster is that you show up physically.
"I thought we did that and everyone was throwing their bodies on the line."
The loss leaves Munster three points off a top-four spot with three rounds to go.
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