I weigh daily and the scale can be one cruel cruel mistress
Days you think you will be up you are down and vice versa. Even if I know I've had too much salt and that I might have retained a bit of water, I cringe a bit when I see the weight go up.
You might know rationally that it isn't really weight gain (fat), but you know emotionally that seeing a higher number sucks.
The good news is that pound will go away when the real weight loss catches up!