The Magpies scored the only goal of Tuesday night's League One clash in the 35th minute when Enoch Showunmi tapped-in after good work by Andre Boucard and Jamal Campbell-Ryce.
However, the home side had Gary Liddle to thank after some heroic defending saw him clear Matt Smith's goal-bound header off the line after 57 minutes.
Dickov, whose side host Liverpool in the FA Cup on Sunday, said: "First half we were sloppy and we didn't get anywhere near them that often. I said to them at half-time if any of them thought they would be playing a full game they would have to improve and if I could have made more changes I would have.
"After they had a bit of a rollicking at half-time they came out better in the second half and gave it more of a go and could have got something.
"We have all got to learn that you can't just turn up on a match day and just expect things to happen, and maybe have one eye on the next game. You've got to look at what's happening now and do things properly and they did that in the second half."