Anmol,a lot of babies skip roll over altogether. My baby dies that occasionally. She is more interested in sitting ,standing,diving and walking. So don't worry..Every kid is different and let them grow and practice the skill that they like. If she is active otherwise then there's absolutely no need to worry.

Don't worry ,every baby has its own growth clock

http://app.babychakra.com/question/50042?ref=Ne2cf7e&

http://app.babychakra.com/question/48649?ref=Ne2cf7e&