Too early to say. Five is a pretty small sample. Have you queried before, to know what to expect? Have you workshopped your query at all?
You may have already, but if not, check out
Query Shark. The blog is run by agent
Janet Reid, and she pulls no punches. If you've read through a number of posts and feel you're hitting the right marks, you might think about strapping on your helmet and then cowering in a corner over at
Query Letter Hell, here on AW's
Share Your Work (SYW) board for a little while. Password is "Vista." Folks will be happy to give you very direct, lovingly cut-throat input on your query.
But, five? If you've already done all this--or are confident you know what you're doing--I'd probably let it go to ten, but don't query any more of your dream agents for now, maybe? Hit some of your "solid" choices? It's so hard when you've hit the agents you want to work with most, and then find out you sent them a sub-awesome query. If you start getting requests, start sending to your top pics.