Cucumber - what looks like rust. young plant imgs

Hi, still new to all this branching out a bit this year did a sunflower, tomatoes, radish herbs etc, this year going for sweet pepper and sweetcorn together, got a couple varieties of tomato and some strawberry for the kids. my question is about the cucumber which I thought id also try, it is a young plant and only has one 'true' leaf, the rust like seems to be on the first leaves but not on the true leaf.

All my stuff is grown on a balcony in pots/planters once ready to be planted out, good 8hrs of full sun available.

I would like to know if I need to do anything with it now, or just let it grow till there are many more true leaves and then remove the rust ones?

Any help and advice appreciated.

 

looks pretty normal to me.
Not rust as far as I'm concerned.