Hi,
No you'll be fine, what you need to be careful is the opposite actually, that depending on the contract you sign with the client, he would own all the code you have used, and that could backfire. It's very very unlickely, but something to know.
You can append the source of the code at the top of scripts if you want to protect them code to fall into ownership of your client.
Bye,
Jean
Bye,
Jean