Canceling selection of a min. 3x3 room leaves a blue mark in prop place

Windows 10 64 bit, AMD 7800, Core 2 Duo Q9k, 8 GB RAM

Build 1.6.3

Nothing game breaking, but something like this below happens sometimes for Raskos and Empire themes when you select tiles which you want to place room on and than cancel selection, on different maps and it seems saving and than loading the game fix this. Also if the selections is red (can't afford to build the room) nothing like this happens.