Goals from Ryan Brunt, after just five minutes, John-Joe O'Toole and Eliot Richards inflicted promotion-chasing Albion's first defeat in eight.
"We started slowly and to be honest Rovers could have been further ahead early on," Rowett said.
"In the latter part of the first half we got back into it and felt we might have had a penalty for a foul on Billy Kee, as well as creating a couple of chances.
"Overall, we weren't at our best. But all the top sides are struggling to put results together at the moment and we knew there would be setbacks along the way.
"There will be more over the last 10 games, but what we need is to produce our best form often enough to get the necessary points."