Yes it would definitely be the issue , you will need to replace the valves
The recommended settings for your bike would be
INTAKE: 0.006 in.(+/-0.001 in.) / 0.16mm (+/- 0.03mm)
EXHAUST: 0.011 in. (+/- 0.001 in.) / 0.28mm (+/- 0.03mm)
So your intakes are way too tight , you can maybe adjust them a few times before replacement , but you will only get a few rides before it moves again , which means they are at the end of their life span
You can either replace them with the stock (or aftermarket) Titanium intakes if you are racing , but if you just ride to have fun on the track , or just trail ride , or are not worried about the weight difference of the Titanium Intakes , then you can go to Stainless Steel Intakes and save yourself a ton of maintenance , since the Stainless will last several times longer before needing adjustment (i have gone 7 years without needing a adjustment on my 450X and just switched to Stainless on my 450R this past winter)
You will usually have to replace the springs with the Stainless since the weight difference requires stiffer springs to avoid valve float
General replacement (usually requires replacement of springs, and retainers as they are considered wear parts , but going to Stainless (or Titanium) you are better off getting a matched set , where the springs are matched with the valve weight
Again , if not seriously racing , i would go the Stainless route , depending on the shops in your area you might want to consider sending your stuff to Ken here (i am in no way affiliated with CRF's Only , but i do trust his work and his prices are very competitive and better than most shops) , but he can either send you a complete ready to go head in your choice of stock to full race porting and machining , or he can redo yours , from mild to wild depending on your budget or specific needs , or as mentioned you can support your local shop , but be warned that a "automotive" shop might not have a clue how to do valve jobs on these 4 strokes (some do , but most do not) , they are not the same as a car head no matter what they tell you , nor do they use the same tools as the automotive heads do , so the shop must be experienced in working on these heads or just say Thank You , and walk out the door
So check around and find someone that is highly recommended for doing 4 Stroke Heads , not just car heads , this will make or literally break your engine if its done incorrectly , when a valve cuts loose because the head was not done right , it takes out everything , head , rod , piston , crank , and possibly cases , so be warned... do your research before sending your head , or leaving your bike at a shop for machine work ...
Here is Ken's head work and prices:
http://www.crfsonly.com/catalog/index.php/cPath/258