System Rom Size - Rooted 6.0

Quick question - I am on MM 6.0 and have just rooted - when I load Titanium Backup it shows the following -

System ROM: 2.06 GB ( 17.1 MB free)
Internal+Media 24.7 GB (24.1 GB free)

Doesn't the System ROM seem low on "free" memory? I don't remember what it was on 5.1. Anyone shed some light on this?

Thanks!