I have had patients that tell me the same thing but it's uncommon. In general, like the other posters, it gets worse temporarily.What you're describing is probably explained by the fact that your chronic rhinitis (or non-allergic rhinitis) condition is improved since using CPAP. This is a neurological imbalance of the involuntary nervous system. Many sleep apnea patients by definition have this and it can present as allergies. It responds somewhat to allergy medications so you don't know what you're treating. It's been shown in a recent study that people with laryngopharyngeal reflux disease (and obstructive sleep apnea) have a relative hypoactive state of the sympathetic nervous system in the nose, with a relative hyperactive parasympathetic nasal nervous system. This is what makes the nose chronically stuffy or runny. The CPAP machine's humidification and filtration system helps too.