Dripping noises in the early morning

I bought a small house from around 1920 equipped with a modern central heater. The problem I'm having is that in the winter each morning when the heater starts to heat the house I hear dripping noises coming from different places behind the walls and maybe from under the floor. It's difficult to locate the sounds as it seems that they never come from the same spot. The pipes are hidden behind double walls. The inner walls are thin wooden walls so you don't see the pipes.
I think this might coming from the condense that the warm water produces when it goes through the pipes. Is this possible?
I'm wondering if these drops can become an issue in the long run.

It's more likely to be expansion and contraction in the walls. Anytime you change temperature, things expand, and as they cool they contract.
That creates a lot of rubbing of materials back and forth, squeaks and clunks, some sounding like drips.

If you hear ticking noises it is as Terry says...
If you hear water gurgling in the pipes you need to purge the air out of the system.