I would have the evaluation done. It really can't hurt and I assume that you are being referred to an expert in ASD. If your child is displaying symptoms early therapy and intervention can be very valuable and make a difference, provided the expert feels they are necessary. As parents sometimes we are to close to our children to see red flags and an outside opinion can be helpful. The evaluator could just as easily say nope, everything appears fine. Then you have peace of mind about any quirks.