Both of them were so absorbed by what they were doing that Tubacca and what might be going on there had no more immediate meaning than the words in the books which had ridden to the Stronghold in Drew's saddlebags.
Both of them snapped to attention when Tubacca was mentioned.
mnli hypothesis: Both of them snapped to attention when Tubacca was mentioned. premise: Both of them were so absorbed by what they were doing that Tubacca and what might be going on there had no more immediate meaning than the words in the books which had ridden to the Stronghold in Drew's saddlebags.