Magpies goalkeeper Bartosz Bialkowski turned a Jon Taylor cross into his own net with nine minutes remaining.
Luke Rodgers had earlier fired Shrewsbury ahead against one of his former clubs, before Lee Hughes and Jamal Campbell-Ryce turned the tables to edge the promotion-chasing visitors in front by half-time.
Curle, whose side are now unbeaten in 22 away matches, said: "I don't think Bart was really tested in the second half.
"The cross took a deflection and the ball's swirling. It could have gone anywhere but unfortunately it wrong-footed Bart.
"All he could do was get a hand on it and the only place he could steer it unfortunately was into his net rather than round the post."
County have dropped down to 10th place but promotion remains the target at the halfway stage of the season.
"Now is the time as a football club for us all to take stock and have a look where we are," added Curle.
"There's been a lot of commitment, a lot of dedication, a lot of hard work going on and you look at the games we've had and we could probably have done with another eight points.
"With another eight points we would be right in the mix."
- Sports & Recreation
- Bartosz Bialkowski
- Luke Rodgers