There are some ways that this could be a problem. Some that I've seen in my own gaming career include:
- The player that always plays Elfs (or whatever race) can be a difficulty if the GM is doing something non-standard with that race.
- The player that always plays the Wizard can be an issue if someone else wants to do the same, throwing party balance off (in systems where that matters)
- Your GM may just be fresh out of ideas to make your preferred role interesting.
- Your characters all start to look alike. (I really have seen the 'Bob Jr' situation play out, with Rana Pippiens [sic], Killerana, and Rana III as I recall.)
This is, of course, a personal experience-based and therefore non-exhaustive list.
However, even though I've seen all these happen, they are still ALL HYPOTHETICALS for you, and serve mainly to provide a new angle for the introspection you are already performing.
The hard bottom line, as other answers also indicate, is this: If you're having fun, and you're not accidentally interfering with the other players' fun, then there is no problem. And you can always ask the GM or consciously step back to create your player last, for the next game, to see if anyone wants the slot you usually occupy.
The meta bottom line, though, is this: If you read all these answers saying there's no problem, and you agree with them, but the issue still nags at you... then maybe you're just getting a little bored or twitchy, subconsciously. In that case, my advice is to try something with a low overall impact-- play something against-type in a convention game (if that's something you do) or a one-shot (if you can get your GM to run one) or consider GMing something yourself, possibly a short game or a one-shot. That is how I try out new ideas I am nervous about, and I think it may be valuable here, as well.