I've got LHR-YYZ-LHR in J coming up, booked in Nov '23 as a reward flight saver: 85k Avios, £350 and a 241 voucher to halve the Avios as a solo traveller.

This week I've been considering moving the outbound to ORD and/or changing dates, so looking around for availability. Much to my surprise I see ORD and YYZ each require 80k, not 85k, Avios each way. Was I somehow overcharged 5k Avios? My first thought was that the price had somehow dropped, but I see redemption charts saying it was 80k on, for example, HfP from last February.

Edited to add: both my outbound and inbound dates are off-peak, and to the best of my recollection were at the time I booked (I'm flying midweek both directions in mid-April, and only looking to move by a day or two). Perhaps my memory is more fallible than I think, and the peak/off-peak calendar has changed in the interim? If so, it seems possibly worthwhile to cancel and rebook (£35 for 5000 Avios) ... ?