I'm quite sure there are several forks.
I have a wallet with 4 connections on block 2799
and a second one with the nodes from the OP on block 4791
100 blocks ago (@4678) my wallet was synced with ypool, but around block 4800 they took an "own way" and have now a difference of >50 blocks.
Definitely there is something wrong...
Wallet code needs checkpoints until you get more nodes. If dev can implement it, dynamic checkpointing will help a lot.
Other option is to set up 2 seed nodes that use connect= in .conf to connect to the mining pools. If wallets use the seed nodes this will reduce the chance of forking probably caused by the latency between pools or solo miners.