So long as all the old urethane was cleaned off and the surface prepped correctly the new glass will seal just fine. Not to mention that urethane is just squirted out of a Milwaukee caulking gun by an associate at the factory, then flipped over on a rotisserie before a suction powered lift assist run by another associate, installs the glass. Plenty of MS fail the "hurricane" water test only to have the glass reinstalled the exact same way.