The nurse told me similar thing, she asked me to try to take novorapid 15 minutes before I have my meal. She thinks the sugar enters my blood before the novo kicks in ( if I am using the correct phraseThis could be the reason also. It’s also not outwith the realm of possibility that your Bolus was incorrectly timed, and missed the spike and then hit after the spike.
There’s various contextual information you’ll have (and which we don’t) which will help you assess which is most likely.

Thanks a lot