Normally the salary dues are settled within a month after a person leaves the organisation with proper notice. But at times in practice in several organizations, it takes extra time. Possibly due to errors in handing over /taking over of company property or charge or whatsoever.
In your company case you are taking a month or two extra and that can be explained as to why the delay. There is nothing legal or non-legal about this and if an employee questions legally utmost you might have to pay the interest thereon. But I see there is no problem at all. It is reconcilable.