That concept has already been discussed more than years ago, and even when the price was less than $250 everybody was saying that it was a bubble because it came from $1 to $100 in a few years.
So no, there is nothing to be worried about.
This bubble issue is the oldest and most argumentative issue of all time in Cryptocurrencies. Lots of the most respectable personalities in the world says that "Bitcoin is a bubble" but now they make themselves regret. As long as many people are supporting this coin it will never be a bubble.