As Trevor says, if you are happy with the price you are charging then don't worry too much.
As a general rule, WFP is faster than trad, but has higher costs, so pricing should be about the same for most standard work.
Out of curiosity, how many windows in this semi and how much are you charging?
Without knowing your location or price, my own charge for a fairly standard semi (about 10 or 12 windows including doors) is around £10 to £12 and I rarely ever get a refusal at that price.
Ian