did i wrong?

yesterday night, after frisbee, we go mmu corner there eat our dinner...something did happen... and it still recall in my mind... non-stoply.
The taukeniu, who sells the drinks came and asked for order. That time, we combined four tables together; actually two tables were from that taukeniu but the another two were not. She told us to move to the back and she is combining the four tables for us. (we are unwilling because hers drinks is always the more expensive one). Anyway, we still moved finally... haiz...
The nightmare...
then i ordered bali ais as usual. When my drinks come, she gave a warm bali, and i said what i ordered is bali ais... then... she poured the bali to the another cup of ais which is for cola one... and... the bali is left half cup... i am... speechless... i thought of God... so... i chose to say nothing and i didn't even planed to request for the another half bali she took away. I dunwan to have any quarrel with her.

This is nothing actually, but... i... purposely didn't finish the water... as it was just a cup of cold vain water... no any bali...  did i wrong?
The taukeniu came to collect the cups impatiently... while i refuse to drink the water left in front of all ppl. did i wrong? should i just keep quite and drink all the water remain? Maybe i just wanna try to gain some self-respect as a customer from her. Finally, yup, she took away the cup. but, before she left, she said to the guy beside me... "what god are you worshiping?" which had made everyone stun for a while... (the guy beside me made his plastic fork and spoon stand on his polystyrene dish)
I felt guilt... i shouldn't did what i shouldn't did, isn't it? did i did wrong?

Somehow, people thought that i am a good christian that know how to do things to be right... but, i not as good as they thought. I still fall down, and sometime, i can't respond to questions that related to God. I am not strong enough in my spiritual. Maybe i am still a baby in my growth to be a good christian. I am not good enough... so... that's y i need God, to lift me up when i fall down... please, help me!! i dunwan to be the stumbling block to others. Please, forgive me, Father God~