Small light brown spots

Anybody know what these spots are? They just appeared overnight. Other than this they are healthy enough

They look very healthy.
Do only a few leaves on one plant show them or many leaves on one plant or many plants etc?
Maybe you splashed some feed on them?

I have had that issue in previous grows. I think it may be related to the type or concentration of my nutes. Check your runoff tds or ppm. My guess is your number are high