No, the problem probably isn't that you "imported" it. It's more likely that you forgot to set something in the project settings. First, here's what you maybe forget to do:
Project → Project Settings → Turn on Advanced Settings (checkbox in the top right) → Go to Rendering → Textures → Set Default Texture Filter → Nearest
I'm also not sure, but maybe this:
Display → Window → Stretch → (Mode → canvas_items or viewport) and (Aspect → keep)
Try this. As far as I remember, this should help. If it doesn't, I'll have to learn Godot all over again.