Quite often I'm offered a shower before or after a booking, whether I accept depends on how I'm feeling or what I have planned next which could be a gym session, other life commitment or for all you know another booking. A shower after sex can just feel nice, or we may have gotten sweaty, or there may be body fluids on my skin which I don't want to get on my clothing.
Occasionally I've asked but I don't expect one, in the case of body fluids I'd just have a standing wash if a shower isn't possible or an option.
Similarly if I think I need one on arrival I'll ask once again I may be coming from another life event, for example I have some regulars I see when in their area for civvy meetings, and there's no other way I can shower beforehand but generally whenever possible I aim to arrive fresh enough to start.
Lots of reasons, and as suggested you are likely to be reading too much into it or feeling something yourself?