Question

When you work out hard enough to get sore your muscles retain water to repair themselves. Therefore, it's completely normal to gain a couple of pounds after an intense session. It should disappear after a few days but by then you'll have worked out again (hopefully!) and the cycle repeats.

In any event, weight loss isn't linear. Don't expect the number on the scale to slowly get smaller. It will drop more on some occasions than others and sometimes might even increase. As long as the overall trend is downward, you're doing fine.