Veteran striker Kevin Lisbie scored the only goal in the first half but after the break Orient weathered a Stevenage storm to ensure they smuggled the three points back to east London.
"Well it's just a really good result for us - it keeps our momentum going," said Slade. "When you come to places like this you have to have the right mindset and be physically ready.
"We had the best chance of the game in the first-half which we took so I think we deserved the win.
"The defence was really solid, we only had one scary moment to deal with and we did that well.
"Every game is important, especially when you have the type of momentum we do. We have a good feeling around the place and we want to keep that - and you do that by winning games."