Butt dimples? Cellulite or bc of exercise? ?

So, i recently discovered (my boyfriend actually discovered it by touching my butt) but.. there is an indention on my left cheek, upper butt cheek. But not like directly on my back a little farther down. My boyfriend kept calling me dimple bc of it.. it kind of made me a little insecure. And it recently got there bc ive always had a bubble butt but that was before i was exercising everyday and eating better. I lost around 45lbs? Is it cellulite? I've been working hard not to ever have this? Can it just appear? Is it unhealthy or gross?