Is it normal for a horizontal crease to be in the middle of my stomach from the faja after lipo?

It's unlikely a permanent crease would be the result of a compressive garment but it is a sign that the garment is ill fitting. You'll need to find one that doesn't generate a crease in the healing tissue.

If a compression garment is overly binding or creasing in an area, it is likely not appropriate for you.  Long term creasing by a garment could potentially create a binding point that could create a permanent skin crease.  It is important to follow up with your physician to address concerns about post-operative garments and post-op care to guarantee best results.