Two-goal Kerry Mayo left County battling to salvage a point as Brighton turned the Third Division table upside down.
But Horton said: "In normal circumstances, a team in our position would be delighted with a point from a game against the champions.
"But we could, and indeed should, have won the game - we had enough chances."
Nevertheless, the draw was more than enough to ensure that rock-bottom Doncaster Rovers couldn't pull off a Houdini act, condemning the Yorkshire club to relegation to the Vauxhall Conference.
Mayo's goals on 20 and 70 minutes were matched by strikes from midfielder Andy Hughes on 61 minutes and Gary Jones, who lashed home his 22nd goal of the season in the 74th minute.