Buyers are allowed to leave positive feedback and a low DSR in a category where the buyer in unsatisfied.
For example, if the listing shows shipping within one day and the postmark shows the item was mailed two weeks later (regardless how long it took to get to the buyer), a buyer satisfied with the price and quality of the product may leave positive feedback but could leave a 1 or 2 in shipping time. There is nothing worng with that and eBay will NOT interfere.
On the other hand, if a buyer leaves glowing positive feedback and DSRs of 1 across the board, eBay may investigate and remove the low DSR on the basis the buyer made a mistake and may have misunderstood what a "1" meant.