Someone tried to scam me

Went to Steak and Shake yesterday. Paid with card plenty of times before. Card reader asks for a tip, then they hand you the receipt to sign that also has a tip line. They also have a tip bucket on the counter. I'm used to it, but no one has ever commented before about my lack of a tip.

But yesterday the girl working the counter tried to scam me. It prints two receipts, the long one I sign and shorter one that's my copy. The girl hands me the shorter one and covers the other one with her hand but never presented it to me. So I called her out "you going to let me sign that?" She then crumbled it up and put her hand behind her back. I had to demand again she let me sign the receipt.

She finally came it to me and I do like I always do. A bit fat obvious 0 in the tip line and I write No Tip above my signature. It was like she was trying to hide it so she could put whatever she wanted on it. After I signed it she put it with all the other receipts I could easily see behind the counter from other card transactions.

Before anyone asks, this location has no manager to ask for. It's an odd location. Its inside a not very busy local casino. So the reaturant gets very little traffic. There has never been more than 2 people working at one time, one on the register and one on the grill, and never a manager that I've seen. The location also doesn't appear on the official website when searching for locations. But it has all the official branding and limited promotion items so it is legit. Just odd.