Something unusual has been happening in the D.C. area’s housing market recently. Sales are strong and inventory is low. Typically those factors push prices higher. Instead, prices have been steady the past few months. What’s disrupting the usual market forces? A number of factors are likely at work, but one could be tighter lending standards. Mortgage lenders haven’t loosened their requirements much. That’s limiting how much home buyers can borrow, which in turn is causing do