Yes that is a common and normal behaviour for anything traded in the market and governed by the forces of demand and supply. If you check the commodity market, energy market and even stock market, they do the same which is go up and down. If there is more demand than supply, price goes up and when reverse is the case, price goes down.

For Bitcoin, you are encouraged to hold because by the nature of Bitcoin, even though it drop in price, it will always recover and give you profit. Remember that the total supply is fixed at 21,000,000 Bitcoin which means as the world population increases and the supply remain fixed, the demand will surely outweigh the supply which will see the price going exponentially up as time progresses.