This doesn't happen often.
Swedens highest mountain top used to be the southern peak of mount Kebnekaise. When I was in school we learnt that it was 2,117 meters above sea level. After the hot summer of 2018 the glacier on top of it has melted and stands 2,096.8 meters above sea level (and shrinking). That makes the northern peak of Kebnekaise 30 centimeter higher. The northern peak is not covered by glacier and therefore not affected by warm weather.
(Photo by Mats Hagwall at Unsplash)