Howe's side struggled to get shots on target in the first half at St. James Park, and though they improved in the second, they still could not find the back of the net as they extended their run without a league win to four games, scoring only twice.
"We conceded with the first shot they had in the game. It's one of those moments where you go 'that sums football up'. That can happen sometimes when you're so dominant. One lapse in concentration cost us," Howe told the BBC.
"I didn't feel we needed to totally rip up what we were doing. A goal looked like it was coming. The last 20 minutes was frustrating as we didn't put pressure on their goal, credit to Brighton to the way we defended, but we're frustrated."
Newcastle welcomed back striker Alexander Isak from injury and thought they looked rampant in the opening exchanges, the Sweden international looked rusty, especially in front of goal.
"We're going through a phase where we're not scoring, but the positive is we're creating chances. We can't feel sorry for ourselves, it's back to hard work on the training pitch," Howe said.
Brighton coach Fabian Huerzeler was happy to get away with the win, even if his side had to soak up a lot of pressure.
"In the end, I wouldn't say it was a deserved win, but my team suffered and defended together," he said.
"Sometimes that's football - we didn't deserve to score at the time when we did, but it's great individual quality from Danny Welbeck, I am very happy with him."
