On-loan striker Marcus Tudgay pounced in the third minute of injury time to secure an unexpected 2-1 victory over the Lions, who saw Darius Henderson miss a penalty in the first half and Adam Smith sent off in the second.
"I'm delighted with the performance and delighted with the effort but let's not get carried away," said Hill. "We must take it into the next game.
"We've been working hard all week on what we wanted to do. We had to give Millwall respect as they've been in excellent form and it worked for us."
Hill felt Smith's red card was harsh on the hosts, adding: "I don't think it was a sending-off, and at best it was a yellow. The player was fully committed in the challenge and I like to see tackles. It was a well-timed tackle but I don't think the ref saw it like that.
"We should have managed the end of the game better against 10 men. The momentum was with Millwall but I think that was their downfall at the end.
"It's been a long and frustrating wait since we had the winning feeling. The fans that travelled deserve a lot of credit and they want a team to be proud of."
Millwall boss Kenny Jackett, whose side have now lost two of their last four following a 13-game unbeaten run, was aggrieved with almost every aspect of the match.
"Looking at the key points in the game we've missed a penalty, the sending off was a harsh one which we will be appealing, and the winning goal looked close to being offside," said Jackett.
"When we went down to 10 men it looked like there was only going to be one winner. Going down to 10 galvanised us and we played better so it's hugely disappointing to lose. We were going all out for the win and it showed at the end. The penalty miss wasn't the only turning point in the game but it did have an effect on its outcome."
- Sports & Recreation
- Adam Smith
- Marcus Tudgay