Thats one of those "it depends" tough questions. If the leak is significant, i.e visible running water, then it could get worse and undermine the entire structure. More likely as you described this is a slow leak that over time generally improves with more compaction due to natural forces. However, it may never totally seal. All ponds leak to some extent. It took 2 years for my newly constructed pond to reach equilibrium and yes I still have some small leaks, but it is acceptable.
I hope yours turns out to stabilize at an acceptable level.
