Yes, it is strange, but this is probability. Many people told me that they were lucky with the pool, then they disconnect and didn't find any block in solo for multiplies of average time :-). My advice - choose solo or pool (depends on personality and hashing power) and keep it. Switching from pool, when you feel lucky and connecting to the pool, when you feel unlucky is the road to the hell, you are cutting your reward by bad management :-).

I found 80 blocks (=4000BTC) for the pool and my total payout is 4017 BTC, so I can say it really converge to expected reward distribution :-).