One cent tipper?

Hey guys, just wanted to pick yalls brains about this regular customer at my job. I work at a brewery that primarily serves beer. There’s a semi regular customer that comes in, and every time she comes she leaves a one cent tip. We have counter service and use a tablet that the customers interact with to leave tips, it gives them several percentage options and an option to do a custom tip. This customer is going into the custom option and typing in that she wants to leave a single cent. Some of my coworkers think that she believes she’s leaving a dollar - she usually only gets one or two pints, so a dollar is an acceptable amount for the tab she usually runs up (could be better, but it’s not as bad as a penny). This has been going on for a long time. Do you guys think i should ask her about this? Should i just be quiet and let it continue? I’m not super worried about the money, i feel like it all comes back around eventually but it’s just so strange that she’s doing this. Asking customers about their tip is just such a delicate thing to do, i was just hoping to get some more thoughts on it.

Edit: You can tip nothing. We sell packs of beer to go that people often don’t tip on. Also wanted to add that she’s a really nice lady and seems to enjoy her experience here. So idk.