Nasolabial folds after Shurink?

I'm looking for a Shurink treatment as an introductory step, so I've been searching through reviews and getting quotes at various clinics. While reading, I came across several reviews stating that their nasolabial folds actually deepened as a side effect. Why does that happen? I already have slight nasolabial folds on one side, so I'm worried that getting Shurink might just make them worse. Has anyone actually experienced this?