Clayton McDonald's ninth-minute strike proved decisive and the Bees are now just two points shy of the League One play-off places after 16 matches.
Rosler said: "In the last 10 minutes, with five minutes of injury time, we never looked like we panicked. We tried to press them high up - that was the plan.
"We tried to keep them away from our goal and it was magnificent. The players dug in big time. We kept very good possession in the last five minutes."
Rosler was forced to substitute Tom Adeyemi due to a hamstring problem as well as his replacement Kevin O'Connor, who was carried off with an ankle injury.
"We've lost Tom for a couple of weeks - O'Connor maybe longer," Rosler added. "I'm very emotional now because Kevin does not look very good."