Sometimes I meet friends after a long time. I’ve known for at least a decade, but I get shy and don’t know how to act around them for an hour at least. What’s this called?

Marketing at /starknet Foundation 

Send me cat memes

might be due to individual growth and experiences 
You’ve been away from them and in that period you’ve experienced lots of things and have grown in different ways (same for them too) so when you meet them, there’s the feeling that

1) maybe they no longer see you as that same person they knew before 
2) maybe they are no longer the same person you used to know