Skill jumped big during an ingame event

My sim was invited by a friend to a danceparty at the Ancient Ruins. She lives in Brindlewood Bay at the moment and was mourning as she lost her husband. The husband is a playable ghost in the household and went allong to the party. The two toddlers went to daycare. While dancing she jumped from level 2 in fitness to level 7 in a heartbeat during the dancevent. No mods installed at the moment and all packs/kits are in play.  Not mad about it but it isn't what it should be.