How does the author use foreshadowing in Stormbreaker?

In Chapter Seven, Alex finds a piece of paper Ian Rider left behind, almost as if he had known what would happen. Alex has no clue what the paper means, but he keeps it with him anyway. Later Alex overhears talk of a delivery expected late that night. This foreshadows an attempt by Alex to find out what the delivery is. However, Alex is caught by Vole, his escort, leaving the reader wondering if Alex might not be discovered before he can learn the truth about the Stormbreakers.