What am I doing wrong that is making my dishes spicier when served as leftovers. Am I not simmering long enough? For some reason the last three dishes I've cooked seem to get spicer leftover the next day. When they do obtain close to room temp they've all been stored in Pyrex and placed in the same fridge but cooked in different intervals (weeks apart). All three dishes have been cooked in the same 12 quart cast iron dutch oven. 

The three dishes are from scratch and do contain fragrant spices:


Chili
Jambalaya
Chicken Tikka Masala


All three are tomato based but for some reason they all seem to get spicer as leftovers. After I bring them to a boil I do simmer them from anywhere to 10-30 mins depending on the recipe. Am I possibly not simmering them enough or am I missing something in the process?

When I search for an answer the closet read I could find was: "Why do spicy foods get hotter in the fridge?"
"Capsaicin is soluble in alcohol, but very little in water. Because of the burning sensation caused by capsaicin when it comes in contact with mucous membranes, it is commonly used in food products to give them added spice or "heat" (piquancy)."

Time was your magic ingredient. More capsaicin became soluble. I find rich dishes have no surprise punch reheated:

"Food that's high in oil or fat dissolves the capsaicin, so it can't continue to bind heat receptors. ... Full fat sour cream or ice cream."