A Gareth Sheldon goal had already brought them back to level terms after falling behind on 20 minutes to a strike from Jon Richardson.
"In my opinion they were the better team. We were very fortunate and they were very unlucky," McNab told the Exeter Express & Echo.
"They could have been 3-0 up in the first 10 minutes and we were terrible all through the team.
"We had a bit of luck in the first game and we were even luckier here. I need to watch the video, but I think it will be a video nasty."