S10·E12 Toby's New Shed

At Arlesdale End, Toby’s shed roof is leaking. Thomas thinks it would make Toby most happy if the roof was fixed, and so gets down to sorting out a new roof being built for the Tram Engine. But to Thomas’ surprise, upon Toby’s seeing the new roof, he is most distraught. What could possibly be tugging at Toby?