Agree with what others have said that it won't be an issue for BA, but will it cause any issue when you get back to HKG? Possibly if there's a residency or working visa associated with old passport?
I know I did the 1-day renewal of my passport while back in UK (from US ) recently, and found out that by luck (rather than careful planning) that my Global Entry runs purely off my Green Card number rather than my passport number.