The Os needed a late Scott McGleish penalty, after Femi Ilesanmi was sent off for bringing down Paul-Jose MPoku, to cancel out Danny Green's 12th-minute strike.
"Our goal took a long time coming and it was a frustrating night in many ways because Dagenham took every opportunity of killing the game whenever they possibly could," said Slade.
"They always try to spoil it, which is the way they play, and I'm not disrespecting that, but obviously their plan was to do anything they could to upset our fluency, and that was their style on the night.
"I thought we played some really good football at times, it was a bit frustrating because we gave them something to hold on to when we conceded after we had started the better side.
"I thought we thoroughly deserved a point, probably more if I'm honest, but you take a point when you're one down with just a few minutes to go."
Source: PA
Source: PA