I want to apologise to one of my teachers but idk if it's worth it

Hello everyone, so I used to be a student of this Chemistry teacher, I only had him for a year because he was new. I had him for Year 10-11 (I'm in the UK so for any americans reading i think grade 9-10. I'm 16.), but I'm now in Sixth Form so I don't do Chem anymore. Anyway, he clearly really loves Chemistry and is great at his job, loves to teach people, and is really kind which is all really awesome and admirable. But there were times where I came into class and ignored him completely, didn't even say good morning or anything and was very clearly looking very out of it, during the last ~2 months of his classes. I was going through some stuff at that period in time (grief) and I feel really bad because in a way I was taking it out on the people around me, including him, even though it had nothing to do with him, or the other people. I want to apologise to him for those times but I don't know if it's worth it because maybe he's forgotten, since he has to teach other classes anyway (like 2 or 3 others)? And I feel like if I find him in school and apologise to him he might not even know what I'm talking about which would be really awkward. What do you teachers think? Should I do anything? It's been weighing me down. Sorry if this is a stupid question