Have you already booked the tickets? If not, would the 3:47PM UA flight (6017) work? If you have booked but your seats aren't showing up and you want the peace of mind, you should be able to change to the slightly later flight now, before a cancellation is announced and beat the rush of others trying to rebook. As someone that lives here, Houston is a wonderful city, but I doubt your trip will be impacted that much from 2 less hours of layover in our fair city.