Any ideas what’s done this?

[weed cutter]

Got some small yellow shiny round spots appeared on a leaf, just wondered if anyone knows what does this? I’m hoping it’s not spider mites or something...?
 

The plants are coming up to 3 weeks old, Have been bringing them on both on my window sill and outside to maximise the sun. It only seems to be one one leaf on one plant but it definitely looks like a pest. Could it be green or white fly maybe?

 

Hoping to plant them out next week but don’t want to if I’m going to need to do something about this.

 

Any advice welcome 

 

[Bartyfartblast]

Morning .... doesnt look like anything I recognise.... have you looked under the leaf? spider mites tend to congregate at the centre of the leaf and once you recognise them you can spot them anywhere little feckers. 

I imagine if planting outside they will get much abuse from local insects as most plants do so put them out .