Hi convair. Although I'm not 100% sure it could well be right that tomorrow's (3rd October) flight has been cancelled. When I left this evening there were some a/c changes on the long haul fleet due to a tech aircraft in the Caribbean, so IAH could well have been affected.

They have protected your seat by holding you something for tomorrow. Unfortunately this is unlikely to be the same seat you had maybe pre-allocated but should be in the same cabin you originally booked. Today's 2025 was also cancelled and all pax put on the later 2027 - however it did not go out completely full so it may be possible to change your seat when you arrive at LGW.