As The Gunslinger begins and Roland is in hot pursuit of the Man in Black across the desert, he feels what is described as a "momentary dizziness" from which he quickly recovers and moves on ("like the world upon whose hide he walked").
As he takes stock of himself, he realizes that some things are gone. His hat, for example, and the horn that had been dropped by his old friend Cuthbert Allgood as he headed into battle on Jericho Hill. The blue of his jeans has been worn down, and he has far fewer bullets. Although he knows all too well the fate of poor Cuthbert, it seems strange to me that Roland seems less concerned with his stock of supplies and how it came to be (or not to be). But of course, going with the flow (leaving it up to ka) is the essence of Roland's nature, so perhaps it's not all that strange.
In his methodical way, Roland recognizes the association between the period of dizziness he experienced and the loss of his friends (and his horn) at Jericho Hill. Only on this most recent reading of The Gunslinger have I realized the portent of this, both the stranger-in-a-strange-land vertigo Roland experiences and the first whiffs of memories he starts to recall.