Quick question: how much leeway does a hole for DWV have to allow for expansion of the pipe?

Installed i-joists under tub expressly for flexibiliity with holes. However the guy who speced them out for me gave me 9-1/2" instead of 11-/7/8", that's a difference of 2" hole vs 4" hole allowed where waste pipe would go. He must have been figuring it was enough for 1-1/2" tub drain, but in fact a 1-1/2" sch 40 DWV pipe leaves about 1/16" to 1/8" leeway around a 2" hole. Do I have anything to worry about when hot tub/shower water goes through that pipe?

I know not to mess with specs on these i-joists, unlike dimensional lumber they just collapse when overloaded.