Yes, you can keep gMSA in different OU.
That should not cause any issue / auth failure.
There was a known issue which is little bit close to your statement. GMSA authentication may report error if DCs are not in Domain Controllers OU.
Here is the reference Doc / fix - https://support.microsoft.com/en-us/help/3094486/kds-doesn-t-start-or-kds-root-key-isn-t-created-in-windows-server-2012