I dont think they did. This is just speculation, because I dont know the details of the contract, but it seems to me that the Texas front office gives out big signing bonuses and smaller base salaries. So by giving a big signing bonus, it makes the Texans look like they overpaid. They did the same with D-Rob's and Babin's contracts this year.
'Anyone ready to go outside so I can make you look bad?' - Matt Schaub talking to the DBs