It definitely wouldn't hurt to put some BitCoins away for a future day when they improve in price against the Dollar.  You have to ask yourself if you want to trade them back to fiat, or, to actually use them for what they are intended - to make payments with.

Only put away what you can afford and make it a regular (ie pay day) top up of the Wallet it's going into.  I say Wallet, because you can't just make it a Wallet Address that your other BitCoins are going into, you have to make it a dedicated Wallet just for savings.