Disk Utility defaulted to Logical Volume Group format for new 4TB HDD and won't let me change to GUID. Is that a problem?

I just installed a 4TB HGST HDD in the 4th bay of my mid-2010 mac pro (2.8 GHz Quad-Core Intel). I formatted the drive using Disk Utility's "Erase" tab as Mac OS Extended Journaled and the drive seems to be working fine (set up as Time Machine backup). It is recognizing the full 4TB capacity and the first backup in TM took a long time but all the files are there. However, my understanding is that all drives intended for use solely in my mac should ideally be formatted to GUID. The problem is that Disk Utility formatted the drive to a Logical Volume Group/Logical Partition, so it's not allowing me to change the format type now i.e. when I go to the "Partition" tab in Disk Utility, all of the options are greyed out. Also, the RAID tab does not appear for this drive as it does for the other three 1TB drives installed.

So my ultimate question is this - is it a problem that I can't reformat to GUID? If so, why is it a problem and how do I fix it?

Thanks!