My Forest River (Prime Time) Lacrosse has dual axle weight rating of 8800 lbs. Total GVWR of 9700 lbs, and two 4400 lb axles.
Yes, I believe yours are underrated for the trailer you have. Only question becomes was it sold that way (since you are not first owner) or were the axles replaced by chance. Forest River should be able to answer that. I asked for the original manufacturers equipment listing from PrimeTime and they responded in like 24 hours with the whole listing, including axles and their rating.
Mike