We recently patched on SharePoint servers with Jan 2019 CU on SP 2013 Servers. After patching, the SharePoint build number is equivalent to Dec 2018 CU instead of Jan 2019 CU.
Is it anything wrong?
Couple of things to make sure before any conclusion:
central admin > upgrade & migration > check product and patch installation statuson this page, make sure Jan 2019 KB number is listed as installed for all servers.
if all above check pass then their is no fix in the Jan CU which change the configuration database schema. it is normal, Read more here.