If you're referring to the scene between Kosh and Sinclair in "The Gathering", (Kosh's greeting) that wasn't in the original airing. It was inserted by JMS after the series ended. And I myself think Season 1 was the best of all. It set the stage of everything that came later.
And, it's not so easy to understand exactly what Kosh says to Sinclair, nor, is it really something you're going to remember 3 1/2 years later when you find out what it means, so, yea, not really a big spoiler for the average first time viewer, IMHO, just foreshadowing to show events were always meant to happen a certain way, and didn't just get pulled out of the air randomly, and a nice little Easter Egg for folks to find on a rewatch, "OMG, he said xxxxx, right in the Pilot"
One Day I hope to be the Man my Cat thinks I am
Where are we going? And why are we in this Handbasket?