Somehow I remember reading that same-day flight change/standby is FREE if you are taking an earlier connection than the one you're booked. But if you request SDC at starting point then the fee does apply.

I think there was a footnote before on the SDC rules, but I don't see it anymore.

Anyway, my friend (CO Silver) has a long layover at IAH tomorrow and would like to take an earlier flight to SFO, but I guess she'll have to pay the $50 fee.