PS3 hard drive "not suitable for laptop computer use"?

I recently replaced my old 40 gb PS3 hard drive with a new one, and was expecting to be able to use the old HDD as an exteal drive. I'm currently using it with this purpose, but on the label of the drive it says

NOT SUITABLE FOR LAPTOP COMPUTER USE

. And thus I was wondering if this is actually a real issue and isn't proper to use it as an exteal drive for making back-ups. Thank you.