Out for a day of ridding notice this

I was out riding for over 5 hours today and I noticed by 1/2 threw thet he my clutch became mushy I adjusted it every thing was fine again then I was ripping threw a forest n up a small hill then coast down other side with clutch pulled in correct gear and everything I let off the clutch with gas for it took off about 20 feet then felt like the clutch got pulled again but it wasn't neutral to wham took off for me again grinding noise from clutch or tranny thinking tranny the noise lasted about 1-2 seconds and then was fine my question is what the heck could have happened this happened once with in 5 hours of riding not another issue all day I did ride for about another 2 hours then home

All this being said does anyone think there may be something loose in my tranny or could this be caused by 2 year old clutch plates normally keep bike in top shape but had brand new clutch so I didn't replace it for last 2 years

I just rebuilt it plates looked fine I may need the heavy duty clutch, I'm not sure if mine was and sorry for the grammar it kept getting deleted off my cell