2010 STI – accidentally put green coolant in the expansion reservoir. How bad is it if some has been drawn into the system?

Hey guys, bit of a fuck up and just wanting some advice.

I've got a 2010 STI that's always had the correct blue Subaru coolant in it. I noticed the coolant was a bit low the other day, so I had some Nulon Green Premium Long Life pre-mix and topped it up (33% mix).

I didn't actually put it into the radiator/filler neck, I put it into the expansion tank with the LOW/FULL markings.

The car was fairly cold when I put it in I think. It had been sitting for probably 3-4 hours after driving, and it's now been sitting for about 2 days without being started or driven as I realized immedaitely I had put the wrong stuff in and should have put the blue 50/50 in.

I'm wondering if some of the green coolant could have been drawn back into the main cooling system as everything cooled down. I did fill the resivior from LOW to FULL.

So my main question is: if a small amount of the green coolant has made its way into the blue coolant in the main system, is that actually a problem? Am I risking corrosion or some kind of chemical incompatibility?

Or if I just drain out the resivior, refill with blue coolant it would be fine? Or should I get a proper flush done?

Cheers