I painted my small powder room (133sf) about 5 weeks ago using Behr Premimum Plus interior flat in Celtic Gray. The room has no windows and is exposed to no natural light. Being a contractor for the past 25 years I prepped the walls correctly and even skim coated and sanded with 220 before painting. Yesterday I discovered a scuff by the vanity that would not wipe off. I touched up the spot (aprox. 1 1/2" area) using the SAME PAINT OUT OF THE SAME CAN as the rest of the walls. (I only used less than 3/4 gallon for 2 coats. After applying the paint I noticed it was LIGHTER than the rest of the wall. I figured it was due to it being wet and would blend in within a few hours. Almost 18 1/2 hours later the spot is still lighter. Will this eventually darken? Is it normal for paint to darken as time goes on? Any and all imput would be greatly appreciated. Thank you all in advance. JB