To answer your question, yes, it's troublesome if these textures weren't licensed for you to use freely.
Many of these textures resemble or perfectly match textures from Minecraft's Faithful texture pack, some with what only seems to be color changes or minor modifications.
Are you sure that all textures were made from scratch by you?
If the textures you used were distributed under CC or similar licenses, you have to comply with the conditions they were released under (Credit, compatible license, etc.)
Please read Non-free Licenses for more information about licenses.