The only way you might get in trouble is if you try to sell a straight loop, like if it was too alike the original loop.
For example, if you grabbed a drum loop and a bass loop, you could'nt mix them together and sell the results, you'd have to make a full song and sell it as a full song.
Same applies to images, you can't just make a minor change and sell media, media has to be original. A good example might be taking a lot of digital photos and fixing them to be seamless, this is the sort of media people are interested in - a swirly filter in PS is no big deal, a seamless wall texture is infinately more sellable.
''Stick that in your text and scroll it!.''