You've brought up a very common problem for rifle shooters, but I haven't heard of handgun shooters ever having the problem.
It is caused by the lubes 'lubrocity' changing with temperature, and it pretty much happens when the lube being used isn't being worked hard enough. (2400 fps with hard bullets in a high quality rifle is idle speed for LBT lube. Well, not quite an idle but it will handle at least 2600 fps in most good barrels and up to 2900 fps with a good bullet design, and ambient temps below 100 deg F)
Try filling less lube grooves with the loads you are using, if the bullet has several grooves. Or up the speed if it will shoot accurately with more power and the barrel doesn't develop a bulge or some other serious complaint show up, like blown primer, locked bolt etc. (I'm funnin you here! Watch pressures as you develop up!)
Most complaints of this problem are with plainbase bullets, and normally when shot at low speeds for them even. I like to make pb rifle bullets with several small grooves, if the bullet is long, so the amount of lube can be adjusted, and also, because the more grooves a bullet has the less lead is rubbing the barrel.
I believe quite a few readers would like to hear your comments after trying my suggestions above.