Grinding noise during cold startup

[Ray Sta.Juana]

Ok, I have this noise during startup, most times during the start of the day
but sometimes it happens if I've been parked for a lil bit while I went to
the store or something. It sounded like the it was the starter because it
only happens while the starter is going and goes away when the engine is
running. Well, I changed the oil on my car and lo and behold it went away?
Stayed away for about a week then came back again a few days ago. My
question is should I still consider it a starter problem or should I dig
deeper? This noise came on right after the Streets track event so could that
be a factor? I also think I overreved by downshifting too early a couple of
times so could that be the cause? Engine seems to run fine otherwise so I'm
not sure if I can even tell if I overreved until it blows. Any help is, as
always, appreciated.

Ray
98 Sentra SE