Iv noticed this on 7.19.2 as well.
I could also reproduce this and have reported the following bug to investigate it: 124340: Number spinner does not trigger a change before making several changes.
EPiServer Development Team
This has been reported before, here's the original bug. Linus' report will be closed as duplicate.
I am observing what looks like to be a bug. Whilst in Edit mode on a page and editing a spinner number (e.g. Sort index), the page triggers the 'Publish' alert (top right) when I change the number by at least two. Developing on 7.5 and EPiServer CMS 7.16, CMS Core 7.19.1, CMS UI, 7.19.0, CMS UI Core 7.19.0
Any ideas what triggers this?