Raspberry Pi 3 new install update question

Short version: everything works. I just am curious about a bump in the road.

I just installed Ubuntu Mate 16.04.02 on a Raspberry Pi 3 with a 32GB SD card. On first boot, the file system shows in the welcome screen as already having been resized. However, when I ran updates via Software Updater, I got an error stating, “Not enough free disk space.” The upgrade needs 48 M, but only has 4M on /boot. Most of the other posts I have read about this seem to be situations where someone had accumulated a lot of junk, such as previously used kernels, on /boot, but this is a fresh install.

The pi updated smoothly with apt-get update and apt-get upgrade. After that, the Software Updater shows the pi as being up to date.

So what is up here? Should I file a bug report?