I use a Logitech G502 mouse, which has an optional button that works like a function key on laptops, changing what the mouse does if it is held down.
I use it to change my dpi settings, so I can use the DPI buttons as hotkeys for the gas mask & laser/flash light. If I press the button (which is located directly under your thumb, so it's easy to do by accident.), then press the tac map key and let go, the tac map is stuck on screen until I leave the match.
I assume this happens because it temporarily changes the mouse buttons, but the tac map should be automatically closed if no input is detected.
(This happened with the tac map set to only be open when holding the key)