Noticed that while running (no pain), my left leg seemed to be in circular swing before landing, right leg has no such movement.

This may be several reasons:
when the foot toes off on a pronated position, it will lead to a circular swing as the leg follows through
also, if you have a One leg longer than the other, it may be compensatory for the Leg length Discrepancy.
and if the calves are tighter on one side than the other, you may be compensating by an abduction twist, which leads to a circular swing.

This type of gait, could cause problems with increaced distance and /or pace.