I reported the same thing on another thread earlier today.
http://www.flyertalk.com/forum/20496098-post40.html
I am on BA93 tomorrow to YYZ as well and did the same as Mrs Fruitcake, booked WTP out and back, and had already done an MFU to CW on the inbound leg. Was OpU['ed this morning as well in to CW. As a silver it is unexpected for me as I expect goldsand first in line for upgrades when they happen.
I have similarly high tier points listed in the booking but I will wait and see what actually posts.
Perhaps I will bump in to Mrs F tomorrow!