Calculate Shipping > Checkout > Pressing back > Need to calculate shipping again

Morning,

When I go to the final checkout/place order page, if you go back, it won’t let you proceed to check out until you’ve calculated shipping, obviously if you’re going forward then backwards, you’ve already calculated shipping? Not sure, it appears a little weird so needs smoothing out we don’t want to calculate shipping each time. The order process shouldn’t be held up by having to recalculate shipping.