I think my copy has more than 45 trains for *each* color, and their number are the *same*.
I think the publisher includes some extra just in case the owner lost or break some.
I completely agree. In earlier TtR copies, there have been exactly 5 x 48 or 3 x 45, so now we were surprised to see this odd distribution.
This, however, must be the most unimportant thread in any BGG forum...