Yes, that is normal. You lost about 6% percent battery charge during the time it was asleep (your Mac draws battery power in sleep mode to power the sleep indicator light). The 80% you saw was the last reported battery charge when you put your machine to sleep. When the System has fully loaded and refreshed its readings from the battery system, it reports the current charge (74%) which is what you have now. You did not suddenly drop 6%, but you lost 6% in the time in which your machine was in sleep mode.
Hope this helps