K.
No don't be concerned. I always "ran cool" too. Your temp is lowest very early in the morning and goes up the later you sleep. I never got a BBT above 97.5 even when I was pregnant (and it was more like 96.5 when I was TTC). It's possible that a very low BBT is indicative of being hypothyroid, but if you've not had any symptoms of this and you haven't had any trouble conceiving I doubt this is the case. You probably just run cool too.