I just attended a quilt show in Ocala, featuring world wide quilts, mostly small wall quilts. Nearly all were densely quilted, and nearly all had waves or even cupped when densely quilted. ( They were likely blocked flat originally, but have been packed/shipped to various shows) l think it's the density of quilting. Wash, dry o damp/almost dry, & steam press around te binding area...chances are the binding will shrink a bit & fix the outer waves anyways. Gift it... baby will not care. Next time, quilt less densely...it'll feel softer too.