No Moses wasn't sinless. Sin is disobeying God either His commandments, or (then) laws, or disobeying His direct orders. Since no one has took the time to show the scriptures, I will:
"And the LORD spake unto Moses, saying, Take the rod, and gather thou the assembly together, thou, and Aaron thy brother, and speak ye unto the rock before their eyes; and it shall give forth his water, and thou shalt bring forth to them water out of the rock: so thou shalt give the congregation and their beasts drink. And Moses took the rod from before the LORD, as he commanded him. And Moses and Aaron gathered the congregation together before the rock, and he said unto them, Hear now, ye rebels; must we fetch you water out of this rock? And Moses lifted up his hand, and with his rod he smote the rock twice: and the water came out abundantly, and the congregation drank, and their beasts also. And the LORD spake unto Moses and Aaron, Because ye believed me not, to sanctify me in the eyes of the children of Israel, therefore ye shall not bring this congregation into the land which I have given them." -Numbers 20: 7-12
God told Moses to speak to the rock and it would bring forth water. Moses did not speak to the rock, rather he hit it, not once, but twice. Thats why Moses wasn't sinless, he disobeyed God and therefore, was not allowed to led the children of Israel into the promised land.
