Sean Shields scored in added time and that is the reason why they now will travel to Warrington on Tuesday, writes Tom Feaheny.
"They out-worked us, you can't put anything else on it. I'm sure Paul Carden, who I know really well, would probably take all 11 of my players over his but we just haven't worked enough, simple as that," McMahon told Kent Online.
"When you cross the white line, the one thing you can't give footballers is desire. They had more desire than we had today and that disappoints me massively.
"You need to work hard in every game of football. If you don't run around, you can't win games of football and I don't think we worked hard enough. That's from the first minute and then you're always playing catch-up and the frustration creeps in, around the ground, the players with each other, which is natural when you don't start well.
"I thought the players looked tired as well. We've had a difficult run of games and we have been, across the Christmas period, down to the bare bones."
For more news, reaction and action from across the National League, like us on Facebook and follow us on Twitter and Instagram.