Do you have a guaranty on that repair? There's no predicting what will happen with your windshield, but if you have a time limited guaranty on the repair, I would go find a bumpy road and test it. If the crack is going to grow significantly, getting the windshield to flex slightly should do it. It will most likely jump from small to very noticeable in an instant.
135i, SGM, Coral, Sport Package, Auto, Premium Hifi, USB/ipod, Apex EC-7s, PPK Stage II