There's nothing wrong or weird about querying a UK agent, but you need to understand that if they make a deal in the US, you'll pay them a higher percentage of your earnings.
Most agencies today 'charge' (if that's the right word) 15% on domestic sales and 20% on foreign....and 'foreign' is related to the location of the agency, not location of the author. This is because there are extra costs associated with negotiating a deal in a country that is 'foreign' to the agency, such as paying a sub-agent in the foreign locale, needing legal documents notarised, and such.
If your primary goal is to get a deal in the US, you should focus on US agents. If you don't care, or if your primary goal is to get a UK deal, there's no reason not to query a UK agent.
