If sun struck that window in June it might have raised the temperature of the glass to a dangerous level. It only takes a few minutes for that to happen. Localized heat and cold damage look almost the same on most plant leaves. It is often caused by being too close to a window, getting sun during the change of seasons, and being too close to electric lighting. We regularly see people posting photos like this here on Orchid Board.
__________________ May the bridges I've burned light my way.