Leonardo Ulloa headed his second from the corner Robins felt was unfairly awarded, before netting his third straight from the restart.
"For 74 minutes I thought we'd get something from the game but it wasn't a corner and then we conceded," Sky Sports News quotes Robins as saying.
"We can't blame the referee but the second goal led to a capitulation.
"The two goals that followed came as a result of us thinking about the misfortune we suffered. Up to then Brighton hadn't hurt us very much."
The result left Huddersfield in 19th, just five points above the relegation zone.