Damn! Do you have such a good memory!

Sam never expected to bump into Sophie here.

After all, he had never seen her at this convenience store before.

The main feature of a convenience store is, well, its convenience. This implies that only locals frequent it for their shopping needs.

Observing Sophie's current state, 

Her hair was somewhat disheveled and damp, clearly fresh from a shower.

And she was clad in pajamas, the quintessential home attire.

This all but confirmed that she lived nearby; otherwise, she wouldn't have come to the store dressed like this, especially to buy sanitary pads.

Awkward! She caught him working a part-time job here, and worse, his hand was on the very package of sanitary pads she needed!

"How much is that?"

Sophie broke the silence, her cheeks still flushed with a hint of red.

Placing the sanitary pads into a shopping bag, he replied, "That'll be $25. Cash or electronic payment?"

"Cash."