I have just had my engine rebuilt and am now running it in slowly on mineral oil.

I have done 450 miles and have noticed that it leaks oil between the head gasket and the block. It is coming from the front of the engine near which is No 1.

The head was flat when it was fitted and so was the block, and it was put together using a YB Group A head gasket and new normal head bolts.

Does this mean head gasket problem?