Do weeds or grass grow in the joints?
If the pavers were installed properly, with the recommended materials and installation methods, you have created a sterile environment to allow weeds to grow through the pavers. There will still be times when seeds can blow into the top of the joints and start growing in any organic material that has built up in the joints. If this happens, you can normally pull them out very easily or remove them with a topical weed killer spray.