Ok so it definitely has to be a glitch on the iPhone app for the IAH-LAS fares

I checked IAH-PHL and it was fine; both the first class and coach fares were similar.

I just did a coach fare check on the same dates (16 March - 22 March) on IAH-LAS and they are different.

.com is showing the following
$204/$231/$288 for the six IAH-LAS flights and $163 for all LAS-IAH flights

iPhone app is showing the following
same pricing on the six IAH-LAS flight but the LAS-IAH are way different

$162/$200/$225/$253/$312....all up from the $163 on .com