A few decades ago was 30 years ago. I doubt this will factor into your application now.
You have applied…now just wait and see. You have done very well…and could very well be one of the accepted students.
If not, just make sure you have your other applications either submitted or ready to submit.
Your school counselor will send a school profile for your class which usually includes the range of GPAs in the class. The adcoms can glean a lot from that in terms of where you rank. They don’t care at all about previous years classes from your high school.
I’m assuming this is your optional LOR, and you also sent academic references…typically colleges want on humanities and one STEM teacher who have had you in their class as a student.
Good luck to you!