So after doing some more testing, the message in the SMSPXE.LOG:
"BootImage PSI000C7 needs to be updated (new packageID=PSI000C7) VersionUpdate=true"
Appears to be very misleading.
I changed a couple of properties (in this case I changed the custom background image) in the Properties of the BootImage:
It then told me that it needed to update the distribution points, it brought up the wizard recompiled the boot image and I was then set to go.
Thanks everyone.