I think it's perfectly normal. Usually if you have, you'll ejaculate less that day or the next. Considering that you did it three times the previous day it's normal to get less the next day.
Even that isn't always true. I didn't have sex or masturbate for over 10 days once and felt like blowing up when I masturbated, the ejaculate was less than usual...but it was pretty thick. Thickness explains too.