I found out the reason..seems there's a problem when using the 64 gb micro sims.
After powering off the phone and installing the micro sim, and then turning the phone back on, the phone believes it has now been modified.
Had to turn the phone off, remove the sim, turn it back on and then reinsert the sim while the phone is still on and now it reads it as "normal"
Must be a glitch between the software and hardware interface but it seems this is aproblem with 64 gb micro sims..