Trying to translate that. It would be something like "because you're carrying the imprudent trace, of the first oblivion" before those verses the girl was saying "give me that kiss I will never forget" and then in the verse you're asking for she is saying that she already tried to forget another time (first oblivion) the kiss and forget the guy but she couldn't because he's got something that always appears in her mind (that's why imprudent, because it appears in the worst moment) that reminds her of him. If it all makes sense haha Greetings from Venezuela!

When a relationship finishes, someone can still be in love and the memories stay firmly. One expect that the other one don't forget so easy. The phrase is a complaining. I risk changing the phrase for, the best moments we share are stuck in my mind but you have forgotten.

Es una bonita expresion! Entiendo que se refiere a un ''amor'' que lleva una huella sin querer ... Por esto dice ''La huella insensata'' . Mas bien, que siempre lo recordara. Perhaps , she's talking about the one that got away!