Yes, your lighting and wall color will affect your WB. The yellow tinge is a sign your color temp is too hot. If it were a blue tinge it would be too cold. You have to try it out using test shots at varying color temps until you get the results your looking for.
And as Asylum Steve stated as your tungstein bulbs age their color temp WILL change as will their brightness. You will notice it first though with the temperature changes.

Thats odd, I clicked on the wrong forum and wound up answering a question.... glad to help though.

JS