Wrong finish used on paint touch ups

My house was painted 6 months ago. Today I decided to go around touching up areas marked up by animals and kids using the left over paint. Flat paint was used on all walls, but I forgot that we did have one air vent that was painted with egg shell. Unfortunately, I grabbed that can of paint noticing it was the right color, but I didn't check if it was flat.

I happily went around the house touching up and after awhile I noticed the paint wasn't drying and blending.

Now that I have several touch up areas in egg shell is there anyway to go back and touch up with the flat finish without creating a bigger problem?

With an open floor plan with hardly any stop and start points and 18 foot ceilings repainting whole walls is not an option.

 

Welcome to the forums!

Was the air vent painted with latex or oil base? Assuming it was latex, you can paint over the eggshell with the flat paint. The paint will dry slower where the eggshell is [as opposed the the edges] but it will dry ok. This isn't the 1st time walls were touched up with the wrong paint

 

The can does say it is latex paint. I will try an area today with the correct paint and see what happens.

Thank you so much for the reply!!