名媛直播

Hi all,
I am new to this forum and quite green to the bonsai world!

I've bought couple of seedling/starter trees and start growing them for a better future! One of them is an English Oak (as I live in the London, should be the best weather for he/she....don't know yet!) and I realised today that there are some strange, I guess, blisters on the leaves.

Reading online I learnt that if are just blisters, it's quite common during this period for oaks and shouldn't affect the overall health of the tree, but I just wanted to be sure and ask to someone with more experience than me...

Can you please, have a look at the photos and tell me if are blisters or something else...and anyway, how to take care of it?

Thank you in advance!
Luca