And what happened when you attacked? I assume you only ended up facing a Warrior or two...
Well he didnt have spearmen for some reason. Maybe he pursuited an early wonder, i dont know. But i told in another thread that is possible to get 4-5 spearmen before an early horserush, but too bad he didnt.
A good way to ''hide'' the rush is to build/buy all horses at same time (1 need to be hide for several turns). But the classical era discovered by ''X'' message can disturb this idea.