Hobber, I would not worry one second over going to the hot springs back in July. I think it has to be a fairly chronic exposure to heat that makes a difference, not one or two days 2 1/2 months ago.
Obviously, if you can avoid heat, that's always good (so no saying, "well we can sit in the hot tub because it's just this one time" but if it already happened and it was ages ago, I would not spare an ounce of concern over it.
It's always something, ya know??