What implications do we get when we use the past tense? For example, if I say that when I was younger, I used to play football, does this imply that now I don't?
We often make inferences that do not follow directly from what was said, but that do follow if we also take into account the speaker's intent. For example, when a headline says "US Figure Skater Wins Silver Medal," strictly speaking it does not follow directly from that that the gold medal was not also won by a US figure skater. But, given that we also know the newspaper's intent in having maximally informative (or attention-grabbing?) headlines, it is safe to conclude that the gold medal was won by someone from a different country.
It seems that your example is similar -- from the fact that you played football in the past it does not follow directly that you don't anymore, but in most circumstances it is safe to assume that you would have expressed yourself differently in that case.