I don't think I've once used a loop, even just to practice making beats, since I first started making music.
The fact that you asked that question is a good thing. Just think about how many people may have downloaded the same sample pack that you did. Maybe these various loops will be in different pitches, or it'll be distorted or have some other effects, but it's still the same loop.
It's sort of like slapping a preset from a VST into your track without changing any of the parameters. It may work with your beat, but you take the chance of someone saying "cool sound, but it's probably just a Massive preset".
The more customization you do, the more unique your stuff will be. And you won't feel any bit of guilt.