It was even one of the problems of the source material: the heroine was too focused on her problem, in a manner that wouldn't last for years even were she a worrywort. (She wasn't.)
So, how confident is the heroine that she can overcome the problem she foresees? Given she's a bubbly and optimistic type? It will come back to hit her at odd times, whenever it's most convenient to me, and the tension needs to be racked up, but it's hard to remember to pry her loose from it.
The joys of plotting