Gear selector question!

Very quick question I couldn't find an answer in a search.

Could some one explain what's going on..

First gear on my GRiSO has changed, before when I kicked down into first there was no movement, the gear selector was at a firm stop.

I noticed last ride, when I selected first I could push thru it again.

Once I noticed this I was testing it each time in first, sometimes it would be a stop others times I could push thru.

What's changed? something needs tightening? something slipping?

Plunger on the clutch level is probably loose.