At 10 years mine groans frequently with some small pops when the shackles are under load. I make sure everything stays lubricated really well. IMHO - Normal. You have replaced all the parts that wear, as long as there are no broken mounts on the trailer or flex in the frame there is nothing else to do.
Don't take life too seriously, it's not permanent.
06 Weekend Warrior FSC3200, Axles flipped, Bridgestone Duravis Tires
2005 Ford F250 PSD 4x4
07 Yamaha YZF450 White/Silver, 94 Husqvarna WXC610
2008 Polaris RZR 800, 2011 Honda CBR1000RR & one Goffin Cockatoo