It also could be it's just the pattern you're body likes to follow. Stick with it.
Sometimes it just takes the body a bit to catch up with you're doing.
If you want to be super technical about it, weigh yourself every morning under the same conditions, log it on a calendar, (mine hangs above my scale in the bathroom), don't worry about what the scale says, but at the end of the month look at the trends. You're doing this not to make the scale your enemy, or your bff, but because it will help you to see trends and patterns in your weight loss.
You can also compare the scale readings to what you were eating by checking your tracker. This helps to see things like how salt, carbs, more water, less water, more protein, less protein, etc., affect what you're doing.
Doing this helps me, because I don't see the scale or the tracker or the calendar as my enemy or my bff, just tools, like a screwdriver, hammer and pliers. They help me get things done. In a way, it kind of takes the emotional quotient out of the deal, and makes it easier to wrap my brain around.