Difficult to put on?

Help! I completed the playtime dress is a fine wale corduroy for my granddaughter. I saw it on her today and it looked like it fit perfectly. However, my daughter told me it was very hard to pull on -- did I do something wrong? I did top stitch the waistline to keep the seam allowances together. The bodice and waist seem very roomy while it is on. It is disappointing because I know it won't be worn if it is a struggle to get on (she is only 20 months). Has anyone experienced this?