That's sometimes the case with carrier delays. On one of the Notes within the past few years, there was a firmware update to a new Android version that completely broke the compass until a subsequent update a month later. I was glad that T-Mobile refused to pass that along to us.
Usually, though, there seems to be no reason apart from a slow carrier process. I've been manually installing N986U1 updates as soon as they're online, and I haven't had any problems. I've been on the latest (ATI5) since Monday. (If the bootloader changes so I won't be able to revert, I usually wait a few days before updating to see if there are reports of widespread problems.)