North End picked up a point after Iain Hume's opener was cancelled out by Greg Halford's second-half header which left the Lilywhites seven points adrift of safety.
Brown said: "I'm disappointed, to tell you the truth. I thought we were worthy of coming in at half-time 1-0 up.
"But sloppy defending for the goal and free headers in the six-yard box are things I don't advocate at all.
"We've been done on detail, not good play. That's the reason we're not sitting here talking about three points, as opposed to one.
"If we've got one game to go and we've got to win that game to stay in the Championship, I'll take that now."