Check the washer gap with the trailer disconnected or at least with the weight distribution bars off. The gap will be gone once you tension up the bars.
If the bars are snapped up and the washers are tight you can check it also. Get down on your knees and look under the bottom of the hitch head under the washers. There should be a single bolt there that holds the head tilted against the washers. Make sure this bolt is tight.
Have you been adding things into the front storage of the trailer? Little things can add up pretty fast to change the tongue weight.