2017 Corolla SE brief grinding noise at startup

New to the forum but, not new to Toyotas and newer ones making noise. We purchased a used 2017 SE April of this year with 38,000 miles on it. I am curious I have read up some on it about a occasional grinding noise at least that is how I describe it at startup. We currently have 46,600 miles on it. I noticed later in the day when we brought it home sometimes the grinding is a bit worse but, only last a second or so. My question is this normal does anyone else have this problem with a 2014 or newer corolla? I have heard before various answers that it is the starter, heat shield rattle etc etc. It doesnt so much worry me but, it bothers me. I cant really say the temperature is a factor with it its a random thing but, only is really noticeable if the car has sat 2-3 hours and it has done it whether it is 90 degrees outside or in the 50-60 degree range but, it just takes a notion. What I find weird is of a morning there is very little to most mornings no noise upon startup or during the day if it sits much longer than 3 hours it doesnt do it. Feel free to chime in I just want to know if someone knows what this might be so if you can help please do thank you in advance for helping.