Take a look at a 1 year gold price chart in USD.
As you can see the price of gold is going parabolical and this, in fact, is a proof of a bubble forming especially considering we don't have hyperinflation in US. If you don't believe me take a look at the following two charts - first is a yearly price of silver where you can see a decent correction after parabolical rise. The second chart displays Nasdaq index during the famous dot.com boom in the beginning of the current century.
And here's Nasdaq
The most difficult question with all bubbles is this - will we see even higher prices or are we heading for a top. Since this is impossible to answer, I would recommend the following. Set a target price for your investment which for you is fundamentally justified for some reason. When this price level is achieved, sell and be happy that you made profit. Even if the price does goes up after you sold this is all speculative and it might as well go down and eat your profits.
The price of gold will come down at some point. The question is how far can it fly. What is your target price for gold?