Not all dust caps are made equal - the new Inland supplied axles come with sturdy dust caps that resist denting and are made to last for years - the local trailer/hitch store covers are little better than foil thickness, the first time installing them they dented and deformed terribly on just a little force.
Take a long look inside - is there evidence of contamination? grit or water? Its cheap insurance to remove and wipe everything down and repack is anything looks fishy.
I can't guarantee parts ala-carte anywhere are better than any other, just noting you don't have to settle for the cheapest thing made. If you don't like the one you get to get back on the road safely keep looking