Ideally it's nothing. But get it checked ASAP. It is often the case with tongue cancers, that they will send you home thinking they got it all only to have a recurrence in the nodes or similar location. Since you've had a neck dissection (normally a great stop gap) hopefully you're safe though depending on location it could jump the midline . I don't want to scare you but waiting will only cause you more physical and emotional stress. Knowing definitively is something that will help in the long run as it will get you acting on it sooner or allow you to breathe a sigh if relief.
Radiation and chemo is very effective in killing HPV related cancers. Ideally they would have sent you for it from the outset - after you've recovered for surgery as it's a great safety net. Though some drs are ambivalent and want to reserve this form of treatment. Not sure where you've been treated but if you get bad news (which I'm sincerely hoping you don't) being at a CCC is the best thing you could do for yourself. Hugs and best of luck.