When your boat's all strapped down give it a good shake, side to side, fore and aft. See what happens... If the boat moves and the trailer doesn't that's bad. If the trailer moves with the boat then you’re good.
This may sound dumb but check that your cross bars aren’t over loaded. I tried to use two 2x4’s as cross bars the first time I trailered my boat. They did support the weight, but holy cow they were bowed. Luckily a buddy of mine had four more in his yard that he gave me. This distributed the weight better. As soon as I got home I purchased real cross bars and rollers from the trailer parts depot. I bought two of these http://www.trailerpartsdepot.com/Amazin ... %2DCR&tpc=
and four of these
http://www.trailerpartsdepot.com/Amazin ... 0&cc=&tpc=
It did take about a month for them to actually get them out, but oh well.
I also just tried leaving all the shrouds and halyards attached to both the mast and boat. Just make sure they're tied down well and won’t go flying off. This way you don't have to set them all up next time. Bring plenty of zip ties, they come in handy.
Make sure that if your trailer has bearing buddies that they are well lubricated (most boat trailers do to keep the water from oxidizing the bearings thus causing them to seize up. These are located in the center of the wheel. There should be a nipple on the front of bearing. Use a grease gun to pump in grease until the grease pushes the bearing buddy all the way out and kind of gushes out the sides of the bearing (not the nipple). It doesn’t really matter what kind of grease you use, as long as you keep them well lubricated. I did however just buy special “magic” marine grease at the Home Depot yesterday, which was 10 cents more a tube than standard grease. I honestly don’t know what the difference is, but it said that it’s for marine applications. After about ten minutes pull over, get a coke, and feel the bearings. If they’re hot, that’s bad, if they’re cool then keep on trucken. These guys get super hot super quick.
A friend of mine didn’t know about this. After about 15 miles the trailer was smoking, he got out and inspected the wheel which was red hot. When he jacked up the trailer to change the wheel he had no problem removing it, the wheel just fell off. A ten dollar grease gun and two dollars of grease is super inexpensive preventive maintenance.