Mine did the same as Master Nukes. What I figure is, you died in a dungeon on or something while poisoned and your stats sometimes come back as more so maybe when you used it, it restored your stats to what it should be. Say /statistics and see if your real stats with all your items un-equipped is lower than your natural, if so then you lost stuff
Also, you could pray to Gods to get back stats like Ogma and errm....maybe you thought you used percieve self and used something else O.o