Already, the title has set us up with ideas of innocence. We hear spring and we think of new life: flowers and baby birds and first love. (OK, maybe that last one is just us.)
does so rinse and wring The ear, (lines 4-5)
This rinsing and wringing, this making clean, also suggests innocence to us. Think about it: generally we associate sin with being dirty, and innocence with being pure and clean.
the racing lambs (line 8)
What's more innocent than a frolicking lamb? Their presence is like the final stamp on this scene that tells us: Certified Innocent.