1 mob kill, 3 bubles of rest?

So I have a macro to check my rest on alts. It counts the rest on "bubles". 10 bubles is half a level and 30 bubles (maximum rest) is 1,5 levels.
So I log with my mage who has full rest (30 bubbles) and go to Redridge to do some quests (15 level). I get the quest to bring the toolbox from the lake. I go there and kill 1 Murloc..just 1! I use the macro and now I have 27 bubles rest...
How the hell 1 single mob eat me 3 bubbles of rest? I also completed 2 quests (Necklase and tools) but quests does not use the rest xp...
This is the macro btw:
/script p="player";x=UnitXP(p);m=UnitXPMax(p);r=GetXPExhaustion();if -1==(r or -1)then t="No rest."else t="Rest: "..(math.floor(20*r/m+0.5)).." bubbles ("if r+x<m then t=t..r else t=t.."level +"..(r+x-m)end t=t.."XP)"end;DEFAULT_CHAT_FRAME:AddMessage(t)
So I log with my mage who has full rest (30 bubbles) and go to Redridge to do some quests (15 level). I get the quest to bring the toolbox from the lake. I go there and kill 1 Murloc..just 1! I use the macro and now I have 27 bubles rest...
How the hell 1 single mob eat me 3 bubbles of rest? I also completed 2 quests (Necklase and tools) but quests does not use the rest xp...
This is the macro btw:
/script p="player";x=UnitXP(p);m=UnitXPMax(p);r=GetXPExhaustion();if -1==(r or -1)then t="No rest."else t="Rest: "..(math.floor(20*r/m+0.5)).." bubbles ("if r+x<m then t=t..r else t=t.."level +"..(r+x-m)end t=t.."XP)"end;DEFAULT_CHAT_FRAME:AddMessage(t)