IMHO, you should always sign your work, just as you should always give credit to others' work which you have used or which has inspired you. These two principles pretty much rule out accusations of plagiarism and ensure that the source of a piece of code can always be traced.
"Stercus! Dixit Pooh. Eeyore, missilis lux navigii heffalumporum iaculas. Piglet, mecum ad cellae migratae secundae concurras."