Hmm, it wasn't doing that for at least a couple days after I made the change, after which note there was less load on the circuit than before (IOW the hall lights and LC extension are now on different circuits, although the kitchen appliances would still have been the vast majority of the load).. But it is a different breaker than before, so maybe something to do with that. They can go bad like this. (Did you try just replacing the breaker?) It's also possible that one of the appliances started drawing more power afterwards due to having developed some defect. Another possibility is that the hot water pot, the garbage disposal, the microwave and the toaster oven have been getting turned on at once. That will absolutely be enough to blow the breaker. Three together might even do it. In any case, something seems to have changed more recently. But please do let me know what the electrician says. Troubleshooting this sort of thing can be tricky.
Also, is there a GFI in the kitchen (code issue if not)? It hadn't occurred to me before to look, but now I wonder why the panel breaker has been tripping instead of it.
David, speaking of those breakers, I noticed last night that the decommissioned ones still hadn't been removed or at least taped off as you said you would do immediately following our conversation mid-day Monday. Presumably you can have the electrician take care of that as well.
To remind you, the other problem with that circuit (current #7) is that den lights (at least, maybe some receptacles involved too?) is also attached to that circuit, and should be split off ASAP. I realize you won't have had time to look at that after you insisted I stop the work I was part-way through. That's also a code issue as you know, even if it has nothing to do with the current problem. The electrician again, perhaps, although it might be a real pain locating where the circuits were joined.
I wouldn't normally have mentioned you by name in this context on an open list, but I'm following your example. Thanks so much for making it clear how to proceed properly, and for all your efforts.
-- Steve