If it's only 5x5, I would scalp/rake it. In the spring as it's going into its big growth flush. It'll bounce right back, looking good. Occasionally topdress with compost and/or native soil; this jump-starts microbial degradation of dead thatch components. Reduce fertilizer inputs; nitrogen increases thatch build-up.

-B

Thanks for the info Bromus. Will rake it in the spring.

Some thatch (1/2 inch) is good for all lawns, but if the soil is improperly cared for thatch can build up too much. When the soil is kept in a good healthy state, an active Soil Food Web, will keep thatch under control.

Here is a link that might be useful: About thatch in turf