Hi princess,
You're back in Houston? Been a while, thought you lived in DC now.
Yes, if I call for the amenities I will generally tip even though they should have had the stuff there in the first place. I just do it to be nice. If it's a hotel I'll be visiting frequently I generally try to start the relationship with a good tipping policy. I started this habit at the Intercontinental in NOLA about twenty years ago and it really paid off with free upgrades, concierge services, etc.
However, I'm not in business for myself anymore, so I will have to see how my "employer" feels about my generosity