There's absolutely nothing wrong. You can say

1. I watch TV every day (or) I'm watching TV [now].
2. I watch television every day (or) I am watching television [at this moment].

The first, the abbreviation, is more colloquial and quicker to write. The second is more formal in writing, but you can say that in speech as well.

The only plausible reason for objecting to the TV variant would be if it were written in lowercase, e.g. tv, instead of uppercase, e.g. TV. The latter is the correct abbreviation (sometimes TV is termed an acronym) and I would recommend using capital letters in semi-formal writing. However, I do see both forms on the Internet and the meaning remains unchanged.