It's a minor set-back
If you're adding exercise, that's a good thing.
Honestly...? It's 4 lbs. Your weight can fluctuate that much in one day - don't rely totally on your scale and that number.
Do you regularly take tape measurements? Your body could be getting smaller and not show much change on the scale.
All that said, if you aren't seeing weight/size reductions after a while, you're going to need to do some tweaking. Do you weigh and measure your food? Are you certain your calories are where you think they are? Are you eating breakfast? Do you get any weight-bearing exercise (such as walking)?
You'll need to change things up and find what works for you. But I'd recommend that you use other ways to measure your success and progress than just the number on the scale. Sometimes it lies.