I was brought up to respect the gifts of life. Whether for free or paid for, the last drop of anything has the most respect.

Toothpaste, water, rice, body cream, bread… you name it. Those leftovers can sustain a whole poor family. What a waste to go to the trash bin unnecessarily.

So, don't feel bad, it's a good habit in the context above.

Smile..:)
Salam