My friend was reading and enjoying Dreamcatcher by Teresa Breslin at the time.
In these post-Harry Potter days, reading children's books is no longer looked down on. No library shelf is complete without Philip Pullman's His Dark Materials, and The Curious Incident of the Dog In the Night-time by Mark Haddon.
In fact, it would seem that reading books for children has become very fashionable, with publishers repackaging books for those still a little nervous of being considered "childish" in their reading habits.
So now that adults everywhere can be found stealing their teenagers' books when they put them down for five minutes, can I make a plea for us to allow children to read children's books too?
This is not as strange a request as it might seem. In many people's mind books are compartmentalised: board books for babies, picture books for under-fives, short novels and then "proper" books with no pictures.
Picture books are seen as being for the very young, and many are. But there is a wealth of picture books for older children which are ignored because of the same prejudices that assumed that if you were reading a children's book, it was because you could not read very well.
Many times I have been in bookshops and seen parents push children away from the picture book towards the young novel as a more suitable purchase for their age. And yet working in schools with picture books I often find it is the nine to 11-year-olds who get the most pleasure out of a session.
And at home I find that opening a picture book and settling down with my children, aged 10 and 12, is a wonderful way to bring a bit of calm into a hectic day.
So by all means let's continue to steal our children's books when they have gone to sleep, and wander through the magical worlds created by some of the best living authors today.
But let us not neglect the picture books, whose texts can often be like poems in their richness of language, and whose small worlds can often lead us into big places.
Jackie Morris is a children's author, illustrator and painter based in Pembrokeshire, and appearing at Swansea's wordplay festival this week. See www.jackiemorris.co.uk