Bike lurching forwards after releasing throttle

[Willb]

Hey guys, first post!

I've been riding for about a month now so this may be from inexperience but...

When I release the throttle, my bike lurches forward as if I've slammed the breaks on suddenly.
For example, if I start off in 1st and bring it up to where I would change into 2nd but let off the gas instead, it should (I assume) just roll but it lurches heavily and then winds down.
I notice this most when I'm riding at slow speeds following traffic or letting the gas off while going down a hill - it's pretty damned annoying!

I've made sure the throttle cable isn't too loose or tight but I'm not very big built so my weight may have something to do with it - the suspension maybe?

Any input would be appreciated - Chur!