Suzuki Club UK

The gears on my GV are a little 'notchy' going into first /second when cold.They seem quite reasonable once warmed up on the road.BUT,I did a fair few miles of lanes to-day (Thetford Forest) 2nd gear mainly, & it became nearly impossible to engage 1st.( just like a dragging clutch) ,but once back on the open road with the cooling breeze it returned to its normal slightly notchy self.Anyone one else experienced this/any ideas ( oil change ?etc.?)
Cheers ,Mick