Uneven incisor teeth are sometimes a sign that the back teeth have a problem, but this is definitely not always the case. I had a dental piggie who had absolutely perfect front teeth but had spurs on his right sided molars that grew into his cheek and caused ulcers.
The best thing you can do is regularly weigh him and keep a note of weights and dates. You are looking for a trend, if his teeth are a problem then his weight may gradually fall. You also need to keep an eye on how and what he eats.
Is he eating plently of hay? This is often the first sign that things are not quite right.
Other signs are dropping food out of the mouth
Juggling food inside his mouth and pulling strange faces
Pawing at his mouth
Choosing softer food or eating less hay more veggies
If he is eating fine I would be inclined to wait and see, could he have chipped one of his front teeth?
Is he a bar biter?
You can have him vet checked but do find an experienced vet who has done and been successful with Gu8neaguinea pig dentistry. A bad dental can make things worse