It's very normal to gain weight from morning to evening. Remember, the foods that we eat and the liquids that we drink don't magically lose their mass and weight once we chew and swallow them, nor are the immediately eliminated from our bodies. It's very common for me to weigh as much as 5 pounds more at night than I did that morning.
Overnight, we lose water through breathing and sweating/evaporation even if we don't need to get up during the night to urinate. Results? You weigh less in the morning than you did when you went to bed the night before.

I blame overnight weight GAINS on the scale gremlins (may the carbs from a thousand Krispy Kremes find a permanent home on their backsides!).