Si,
The fat content of a meal does slow down the rate of absorbtion, so can delay the effects of the carbs in your meal to a much later time, which you and your dsn already know. Novorapid is almost exhausted at the 4 hour mark, and as your bg was fine up until 3 hours after, I think it will be more to do with your lantus by the look of things. As your morning levels are fine, I would ask your dsn for advice on this matter.
Sorry I can't be more helpful here!
Nigel