It is completely normal for the body to retain water as part of recovery, SPECIALLY when first starting with a work out routine. Do not be discouraged, most likely just your body adapting to the new routine. Give it several weeks, even months, and as you condition the muscles, they will also recover faster and more efficiently. Start easy, and progressively increase weight/load.
It could be due to water retention. You may be experiencing some inflammation due to the muscle workouts, and this can cause slight swelling around the affected areas and weight gain on the scales. This is why I prefer to use tape measure to track my measurements once the inflammation has subsided.
Are you keeping track of what you’re eating? I noticed when I started working out I was way hungrier. Could it be water weight? The swelling the first few weeks definitely showed when I got on the scale.