Student loans do not work the same as other types of debt. For example for most companies if you are 30 days delinquent, they will negatively report you to the credit bureaus. However the Department of Education made a recent change that no negative credit reporting will occur until at least 90 days delinquent. While many student loan companies attempt to hold this information close to the vest as internal information, the Department of Education lists the information on their website here.
The reason for this change is basically a change in philosophy. Previously General Forbearance was given either when you could not make your payment or to cover processing time. But as General Forbearance interest capitalizes and there is only a set amount of time for forbearance, an alternative was searched for. Instead of using General Forbearance for processing time that capitalizes (gets added to the principle), once the form gets processed it will place a forbearance such as an Administrative Forbearance (which is non-capping). This will bring the account current. However because it can take 1-2 billing cycles for something such as an Income Plan to process, it was necessary to take the credit reporting time period to 90 days.