Snake keeps escaping :(

Hello! I got my corn snake about 7 months ago and about a month ago she escaped her enclosure and since then has gotten out three other times (all times I found her within an hour.) I finally found the spot she has been getting out from and secured it but I still am worried that the reason she is escaping is because I'm doing something wrong. :/ I keep the temperature consistent (about 83 on the warm side and 77 on the cool side) and humidity between 50% and 60%. I clean it regularly and change the bedding. I have her in a 20 gallon tank and she's still pretty small so it should be plenty of space.

I also just don't like her being out of her tank for too long since its too cold and dry outside the tank. I know snakes are known to be good escape artists, I'm just a little concerned that it has happened multiple times.