If you are weight training and building muscle that could well be the answer. It's not that muscle weighs more than fat per se (1 pound = 1 pound), but 1 pound of muscle tissue takes up much less space than 1 pound of fat. So, if you lost 2 pounds of fat but gained 2 pounds of muscle the scale will be the same, but you will be much better off!
Measurements are great (as are how your clothes are fitting). If you had a body composition measurement done before, you could compare it to now to see your progress.
If this new routine is new, I guess it's also possible you have lost fat but your muscles are retaining more water (though I'm less sure about this...)
I think the scale is an important tool, but in many ways it is not the best way to measure FAT loss and body composition. Sounds like you're doing well!!
My 5 C's of healthy living: Commitment to conscious control, with the understanding that choices have consequences