Lowe's Home Improvement

So we came to this location to get some light bulbs, but the employee that helped us gave me the wrong prod. I understand that everyone makes mistake. So I came back to exchange. I greeted this lady at the return&exchange with well-manner, but she looked at me like she was going to kill me. Very rude. I didn’t know that I was supposed to go back the return center so I left. Once I realize I don’t have my receipt I came back. That very rude lady looks even more frustrated. I’m sorry that I didn’t know I was supposed to come back to the return center, but do you have to be so rude? I didn’t do anything to you personally. Maybe you have a bad day, but when someone greet you with a smile, you don’t pour your frustration on that someone. Is it really too much to ask?