Acer ginnala - weird leaves

[Krone]

Can someone identify what could be wrong? Have couple of leaves that look like this.

 

[Forsoothe!]

Wuhan...

 

[jeremy_norbury]

It's not enough to worry about at this point.

 

[Gsquared]

My tridents used to have something similar in California. The nurserymen I asked called it “water mold spores”. They said it was a minor fungal infection caused by warm, damp nights. I’ve never had it hurt the tree, just make those few early leaves look a little ugly. It resolved itself once the leaves hardened off.