Is it normal to have altered sensation after a flexor tendon repair injury?

Yes: Anytime you have surgery it is likely and common that sensation is different because the nerves that determine sensation are sometimes cut or irritated during surgery - this is normal and not because the surgery was done badly. You almost always have some very small nerve fibers effected. Sometimes the sensation recovers fully, but sometimes not. Nerves take weeks to months to heal.

Maybe: With cuts deep enough to cut the tendon, one or both of the nerves in the finger could be cut or "bruised". If it felt normal after the injury, but before surgery, the feeling could be from swelling.