Does XP decay? Xp loss/ reverting

I was on my 98 barb and i could of sworn i had 4 bars then i got on a little while ago and i have 3 maybe im just a glass half full type guy

you only lose XP when you die

Why feed this crap…here we go with all the crazy talk and victimized conspiracies

Also it is could have, wtf is could of