I would say yes, that's completely normal.
According to the wiki entry:
It does go on to say, and this is my experience too, that the amount of semen produced is smaller in subsequent ejaculations. That is to say if a particular man produces about 5ml having not ejaculated for over 24 hours his second ejaculation will be measurably smaller. Also, if a man leaves it for a few days it is normal that his 'load' is larger than normal. If your husband goes 2 or 3 days without ejaculating is there any significant change in what he produces?The force and amount of semen that will be ejected during an ejaculation will vary widely between men and may contain between 0.1 and 10 milliliters. (By way of comparison, note that a teaspoon is 5 ml and a tablespoon holds 15 ml.)